A moving coil galvanometer converted into an ammeter reads up to 0.03 A by connecting a shunt of resistance 4r across it and ammeter reads up to 0.06 A, when a shunt of resistance r is used. What is the maximum current which can be sent through this galvanometer if no shunt is used?
An ammeter and a voltmeter of resistance R are connected in series to an electric cell of negligible internal resistance. Their readings arc A and V, respectively. If another resistance R is connected in parallel with the voltmeter then
Voltmeters V 1 and V 2 are connected in series across a D.C. line. V 1 reads 80 volts and has a per volt resistance of 200 ohms. V 2 has a total resistance of 32 kilo-ohms. The line voltage is
The resistance of a potentiometer wire of length 200cm is 10 Ω . This wire is connected in series with a 20 v battery and an external resistance of 30 Ω . What will be the balancing length of a secondary cell of emf 4 volt?
The resistance of a wire is 20 ohms. It is so stretched that the length becomes three times, then the new resistance of the wire will be
An ionization chamber with parallel conducting plates as anode and cathode has 5 × 10 7 electrons and the same number of singly-charged positive ions per c m 3 . The electrons are moving at 4 μ A / m 2 . The current density from anode to cathode is The velocity of positive ions moving towards cathode is
I-V characteristic of a copper wire of length L and area of cross-section A is shown in figure. The slope of the curve becomes
Dimensions of a block are 1 cm x 1 cm x 100 cm. If specific resistance of its material is 3 × 10 − 7 ohm-m, then the resistance between the opposite rectangular faces is
The equivalent resistance of the arrangement of resistances shown in adjoining figure between the points A and B is
A battery consists of a variable number n of identical cells having internal resistance connected in parallel. The terminals of the battery are short circuited and the current / is measured. Which one of the graph below shows the correct relationship between I and n?
In the network shown, potential of the junction O is
A wire of resistance 4 Ω is stretched to twice its original length. The resistance of stretched wire would be :
If 62.5 × 10 18 electrons per second are,flowing through a wire of area of cross-section 0.1 m 2 the value of current flowing will be
In the given circuit if I 1 and I 2 are the currents in resistors of resistances R 1 and R 2 , respectively, then
In the given circuit, the current I 1 is
The energy stored in the capacitor in the steady state is
Consider the circuit diagram shown. Column – I Column – II (i) Potential difference across A and D in steady state is p. 2 V (ii) Potential difference across capacitor in steady state is q. 1.8 V (iii) Value of Q for which no energy is stored across capacitor is r. 0.2 V (iv) Potential difference across A and B in steady state is s. 14 3 Ω Now, match the given columns and select the correct option from the codes given below
Which of these is a FALSE statement?
A potentiometer is used for the comparison of e.m.f. of two cells E 1 and E 2 . For cell E 1 the no deflection point is obtained at 20 cm and for E 2 the no deflection point is obtained at 30 cm. The ratio of their e.m.f.’s will be
The total current supplied to the circuit by the battery is
A strip of copper and another of germanium are cooled from room temperature to 80 K. The resistance of
Which of the following setups can be used to verify, Ohm’s law?
A platinum wire has a resistance of 2. 62 Ω at 15°C and 3.29 Ω at 80°C. Find the temperature coefficient of the resistance of platinum wire.
One filament takes 10 min to heat a kettle and another takes 15 min. If connected in parallel, they combindly take min to heat the same kettle.
The length of a wire of a potentiometer is 100 cm, and the emf of its standard cell is E volt. It is employed to measure the emf of a battery whose internal resistance is 0.5 Ω . If the balance point is obtained at l = 30 cm from the positive end, the emf of the battery is
The masses of the three wires of copper are in the ratio 1 : 3 : 5. And their lengths are in the ratio 5 : 3 : 1. The ratio of their electrical resistance is
The top left and right arms of a Wheatstone bridge have resistances P and Q. The bottom left and right arms have resistances R and S. When R = 12 ohm, the bridge is balanced. Now P and Q are interchanged and R = 27 ohm balances the bridge. The resistance S is
One end of copper wire of length 2L and cross sectional area A is attached to one end of another copper wire of length L and cross section area 2A. If the free end of the longer wire is at electric potential of 8 volt and free end of shorter wire is at potential of 1volt,what is the potential of junction of two wires.
Two similar headlight lamps are connected in parallel to each other. Together, they consume 48 W from a 6 V battery. What is the resistance of each filament?
How will the reading in the ammeter A of Fig. be affected if another identical bulb Q is connected in parallel to P as shown. The voltage in the mains is maintained at a constant value.
A copper conductor of fixed length has a variable cross sectional area. A battery of emf E is connected between the ends of the conductor. If V d represents average drift velocity of free electrons at a section of area A, then
Two ends of a conductor of varying cross section are connected to the terminals of a battery as shown in the figure. 1, 2 and 3 represent three different sections of the conductor. If i 1 , i 2 and i 3 be the current flowing through these sections, then
Two resistances are joined in parallel whose resultant is (6/5) Ω . One of the resistance wire is broken and the effective resistance is 2 Ω , the resistance of the wire that got broken was :
The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of 10 Ω is :
The resistances 500 Ω and 1000 Ω are connected in series with a battery of 1.5 volt. The voltage across the 1000 Ω resistance is measured by a voltmeter having a resistance of 1000 Ω . The reading in the voltmeter would be :
Two ends of a metallic wire of length l and radius r are connected to the terminals of a battery of emf E and the drift velocity of free electrons is found to be ‘V’ . What will be the drift velocity of free electrons when the ends of a metallic wire made of same material having length 2l and radius 2r are connected to the terminals of a battery of emf 2E?
The length of the resistance wire is increased by 10%. What is the corresponding change in the resistance of wire?
The length of a given cylindrical wire is increased by 100%. Due to the consequent decrease in diameter the change in the resistance of the wire will be
The resistance of a wire is 10 Ω . Its length is increased by 10% by stretching. The new resistance will now be
A thick wire is stretched so that its length becomes two times. Assuming that there is no change in its density then what is the ratio of change in resistance of wire to the initial resistance of wire?
An electric current passes through non-uniform cross-section wire made of homogeneous and isotropic material. If j A and j B are the current densities and E A and E B ate the electric field intensities at A and ,B respectively, then
An electric current flows along an insulated strip PQ of a metallic conductor. The current density in the strip varies as shown in the graph. Which one of the following statements could explain this variation?
Two uniform wires A and B are of the same metal and have equal masses. The radius of wire A is twice that of wire B. The total resistance of A and B when connected in parallel is
Two wires of resistance R 1 and R 2 have temperature coefficient of resistance α 1 and α 2 respectively. These are joined in series. The effective temperature coefficient of resistance is
Two resistances R 1 and R 2 are made of different materials. The temperature coefficient of the material of R 1 is a and of the material of R 2 is − β . The resistance of the series combination of R 1 and R 2 will not change with temperature, if R 1 /R 2 equals
Two resistors are connected (i) in series (ii) in parallel. The equivalent resistance in the two cases are 9 ohm and 2 ohm respectively. Then the resistances of the component resistors are
A wire of cross-sectional are d A, length L 1 , resistivity ρ 1 and temperature coefficient of resistivity α 1 is connected in series to a second wire of length L 2 , resistivity ρ 2 , temperature coefficient of resistivity α 2 and the same area A, so that wires carry same current. Total resistance R is independent of temperature for small temperature change if (Thermal expansion effect is negligible)
Consider the circuit shown in the figure. The current I is equal to
Two wires of equal diameters, of resistivities ρ 1 and ρ 2 and lengths l 1 and l 2 , respectively, are joined in series. The equivalent resistivity of the combination is
The two ends of a uniform conductor are joined to a cell of e.m. f . E and some internal resistance. Starting from the midpoint P of the conductor, we move in the direction of current and return to P The potential V at every point on the path is plotted against the distance covered (x). Which of the following graphs best represents the resulting curve?
In the circuit shown, the point B is earthed. The potential at the point A is
Find the value of R for which no current will flow through 5 V battery.
Figure shows a network of eight resistors numbered 1 to 8, each equal to 2 Ω connected to a 3 V battery of negligible internal resistance. The current I in the circuit is
Find the power of the circuit in steady state.
In the circuit shown, the reading of the ammeter is doubled after the switch is closed. Each resistor has a resistance equal to 1 Ω and the ideal cell has an emf equal to 10 V. Then the ammeter has a resistance equal to
A current of 2 A flows in the circuit as shown. The potential difference V A − V B will be
The reading of the ideal voltmeter in the adjoining diagram will be
The potential gradient along the length of a uniform wire is 10 volt/metre. B and C are the two points at 30 cm and 60 cm point on a meter scale fitted along the wire. The potential difference between B and c will be
In the network shown in the figure, each of the resistance is equal to 2 Ω . The resistance between the points A and B is
Three 60 W, 120 V light bulbs are connected across a 120 V power source. If resistance of each bulb does not change with current, then find out total power delivered to the three bulbs.
In the given potentiometer circuit, the resistance of the potentiometer wire AB is R 0 . C is a cell of internal resistance r. The galvanometer G does not give zero deflection for any position of the jockey J. Which of the following cannot be a reason for this?
What should be the value of resistance R in the circuit shown in figure so that the electric lamp consumes the rated power?
A cell of constant e.m.f. is first connected to a resistance R 1 and then connected to a resistance R 2 . If power delivered in both cases is same, then the internal resistance of the cell is
Two wires A and B of same material and mass have their lengths in the ratio 1 : 2. On connecting them to the same source, the rate of heat dissipation in B is found to be 5 W. The rate of heat dissipation in A is
A battery of internal resistance 2 Ω is connected to a variabte resistor whose value can vary from 4 Ω t o 10 Ω . The resistance is initially set at 4 Ω . If the resistance is now increased, then
The circuit shown in figure, contains a battery, a rheostat and two identical lamps. What will happen to the brightness of the lamps if the resistance of the rheostat is increased? Lamp P Lamp Q (a) Less brighter Brighter (b) Less brighter Less brighter (c) Bright Less brighter (d) No change Brighter
A voltmeter has a range 0 − V with a series resistance R. With a series resistance 2R, the range is 0 − V ‘ . The correct relation between V and V’ is
If X, Y and Z in figure are identical lamps, which of the following changes to the brightness of the lamps occur when switch S is closed?
In which one of the following arrangements of resistors does the ammeter M, that has a resistance of 2 Ω , give the largest reading when the same potential difference is applied between points P and Q?
In the circuit shown in figure, the heat produced in the 5 Ω resistor due to the current flowing through it is 10 cals/s. The heat generated in the 4 Ω resistor is
Assuming all bulbs are identical, rank the brightnesses of the bulbs, from brightest to dimmest.
For what value of R, current in the galvanometer is zero?
n resistances, each of r ohm, when connected in parallel give an equivalent resistance of R ohm. If these resistances were connected in series, the combination would have a resistance in ohms, equal to
Find the power supplied by 20 V cell in the figure shown.
A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively
When three identical bulbs of 60 W, 200 V rating are connected in series to a 200 V supply, the power drawn by them will be
A capacitor is connected to a cell of emf E having some internal resistance r. The potential difference across the
we have two wires A and B of the same mass and the same material. The diameter of the wire A is half of that B. If the resistance of wire A is 24 ohm. then the resistance of wire B will be
When a wire of uniform cross-section a, length l and resistance R is bent into a complete circle, resistance between two of diametrically opposite points will be
Statement 1: When a cell is charged by connecting its positive electrode with positive terminal of the charger battery then potential difference across the electrodes of cell will be smaller to the EMF of cell. Statement 2: Potential difference across electrodes in a cell providing electric current is E = Ir, where E is EMF and r internal resistance.
Statement 1: In the given circuit, if lamp B or C fuses, then light emitted by lamp A decreases. Statement 2: In the given circuit, if lamp B or C fuses, then voltage on A decreases.
Statement 1: An electric bulb becomes dim, when an electric heater in parallel circuit is switched on. Statement 2: Dimness of bulb decreases after sometime.
The current in a conductor varies with time t as I = 2 t + 3 t 2 , where I is in ampere and t in seconds. Electric charge flowing through a section of the conductor during t = 2 sec to t = 3 sec is
Statement 1: When current through a bulb is increased by 2%, power increases by 4%. Statement 2: Current passing through the bulb is ∝ 1 Resistance
A torch bulb rated as 4.5 W, 1.5 V is connected as shown in the figure. The e.m.f. of the cell needed to make the bulb glow at full intensity is
A wire of length L is drawn such that its diameter is reduced to half of its original diameter. If the initial resistance of the wire were 10 Ω , its new resistance would be
Current through wire XY of circuit shown is
In the arrangement of resistances as shown, what is the equivalent resistance between A and B?
An ammeter of range 5 A is to be converted into an ammeter of range 10 V. If the resistance of ammeter be 0.1 Ω , then what resistance should be connected in series with it
A cell dissipates the same power across each of two resistors R 1 and R 2 when connected separately. The internal resistance of cell is
Two uniform wires A and B are of the same metal and have equal masses. The radius of wire A is thrice that of wire B . The total resistance of A and B when connected in parallel is
In the circuits shown below, the readings of the voltmeters and the ammeters will be
The potential difference V A – V B between the points A and B in the given figure is
In the circuit shown in fig. the rate of heat produced in the 5 Ω resistor is 20 J s – 1 .
In the circuit shown, the cell is ideal, with e.m.f. = 15 V. Each resistance is of 3 Ω . The potential difference across the capacitor is
Ten identical cells connected in series are needed to heat a wire of length one meter and radius ‘r’ by 10 o C in time ‘t’. How many cells will be required to heat the wire of length two meter of the same radius by the same temperature in time ‘t’ ?
30. The resistance of iron wire is 10 Ω and α = 5 × 10 − 3 / 0 C . If a current of 30A is flowing in it at 20 0 C , keeping the potential difference across its length constant, if the temperature is increased to 120 0 C , what is the current flowing through that wire?
The i–V graph of a conductor at two different temperatures T 1 a n d T 2 is given. Then :
The metre bridge shown is in balance position with P Q = l 1 l 2 . If we now interchange the positions of galvanometer and cell, will the bridge work? If yes, what will be balance condition?
In the electrical circuit shown in the figure, the current i through the side AB is :
Two ends of a cylindrical copper rod are connected to the terminals of a battery and the drift velocity of free electrons is found to be V. Now the copper rod is stretched to twice its original length and the ends of this deformed rod are connected to the terminals of the same battery. Then new drift velocity of free electrons in the rod will be
A milliammeter of range 10 mA and resistance 9 Ω is joined in a circuit as shown in Fig. The meter gives full-scale deflection for current I when A and B are used as its terminals. If current enters at A and leaves at B (C is left isolated), the value of I is
Two cylindrical conductor having same cross-sectional area ‘A’ and but lengths ‘l’ and ‘2l’ are connected in series combination. Temperature coefficient of resistivities of their materials are α a n d 2 α respectively. Then effective temperature coefficient of resistivity of the combination is
In the network shown, if power dissipated in the 6 Ω resistor is 24 watt, reading of the ideal voltmeter V is
In the network shown, power dissipated in 2 Ω resistor is 8 Watt. What will be the power dissipated in 2 Ω resistor after the switch S is closed.
In the arrangement shown, reading of the ammeter just after the switch S is closed is 2 Amp and a long time after S is closed, the reading is 0.5 A. Then the value of R is
In the network shown, equivalent resistance between A and B is
Internal resistance of a given cell is to be found by a potentiometer and the circuit is as shown in the figure. When switch S is open balance length is found to be 250 cm and when S is closed, balance length is found to be 210 cm. The internal resistance r is
In the circuit shown, reading of the potentiometer is
In the network shown the current through 1 Ω resistor is
A potential difference V is applied across a resistor of resistance R. If the voltage across the resistor increases by 1% and the resistance increases by 2%, then the maximum possible change in the power dissipated in the resistor is
In the circuit shown in figure, the equivalent resistance between A and B is
An alternating current having peak value 28 A is used to heat a metal wire. To produce the same heating effect, a constant current i can be used where i is
The maximum charge stored on the capacitor C in the given circuit is
A resistance R 1 is connected in the left gap of a metre bridge and a resistance of 9 Ω is connected the right gap in the metre bridge. The null point divides the bridge wire in the ratio 4:3. Now another resistance x Ω is connected in series with R 1 in the left gap of te metre bridge and this time the null point divides the bridge wire in the ratio 4:1. Then the value of ‘x’ is
A fuse wire should have
Three identical bulbs B 1 , B 2 and B 3 are connected in series parallel combination as shown. Rating of each bulb is 45 W, 100 V o l t . If a 100V supply is connected across the combination, the power consumed by the system will be
Three identical bulbs B 1 , B 2 and B 3 are connected as shown in the figure. Total power consumed by the circuit is ‘p’. If the bulb B 2 is fused, total power consumed by the system will be P 1 . Then
The equivalent resistance between terminals A and B is
The resistance R of a conductor varies with temperature as shown in Fig. 4.57. If it is written as : R 1 = R 0 1 + αt + βt 2
The variation of current with potential difference is as shown in Fig.4 .56. The resistance of the conductor is :
A current of 5 A is passing through a metallic wire of cross-sectional area 4 x 10 – 6 m 2 . If the density of charge carriers of the wire is 5 x 10 26 m – 3 , the drift velocity of the electrons will be:
Electrons emerge from an electron accelerator as a beam having a circular cross-section of diameter 3 mm. The beam current is 6 μA and electrons are travelling so fast that their speed can be taken as c = 3 x 10 8 m/sec with an insignificant error. Electron density in the beam is :
Two conductors, both having same length and same area of cross-section are joined in series. Their materials are different and resistivity of one of them is ρ . If equivalent resistivity of their combination is 3 ρ , resistivity of the other conductor is :
An electric iron draws 10 amp, an electric toaster draws 5 amp and an electric refrigerator draws 3 amp from 220 V service line. The three appliances are connected in parallel. If all the three are operating at the same time, the fuse to be used should be of :
The equivalent resistance between the terminals A and D in the following circuit, is :
If power dissipated in the 9 Ω resistor in the circuit shown is 36 watt, the potential difference across the 2 Ω resistor, is :
In India electricity is supplied for domestic use at 220V. It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, the resistance of a 60 W bulb for use in USA will be :
The time constant of shown RC circuit is :
From the diagram, it can be calculated that the resistivity of the material of the rod is :
Calculate the energy stored in the capacitor of capacitance 2μF, at the instant when the voltmeter ‘V’ gives a reading of 15 V and the ammeter A reads 15 mA. Resistance of voltmeter is unknown and ammeter is 999 Ω .
A battery is charged at a potential of 15 V for 8 hours when the current flowing is 10 A. The battery on discharge supplies a current of 5 A for 15 hours. The mean terminal voltage during discharge is 14 V. The “Watt hour” efficiency of the battery is :
Find out the PD between the points C and D in Fig.
Two batteries, one of emf 18 volt and internal resistance 2 Ω and the other of emf 12 volt and internal resistance 1 Ω , are connected as shown. The voltmeter V will record a reading of :
In the circuit shown in Fig, R 3 is a variable resistance. As the value R 3 is changed, current I through the cell varies as shown. Obviously, the variation is asymptotic, i.e., I ➔ 6A as R 3 ∞ . Resistances R 1 and R 2 are, respectively :
A current of 2 A flows through the network shown in Fig. 5.130. The PD between points Band D is :
In the given circuit, maximum power which can be delivered safely to any resistor is 24 W. Maximum potential difference that can be applied between X and Y, so that all resistances are safe, is :
A current of 2A flows through a 2 Ω resistor when connected across a battery. The same battery supplies a current of 0.5A when connected across a 9 Ω resistor. The internal resistance of the battery is :
When the key K is pressed at time t = 0 which of the following statements about the current I in the resistor AB of the given circuit is true?
In the circuit shown in the Fig, if the potential at point A is taken to be zero, the potential at point B is :
Two identical electric bulbs, each of rating series and a 200 volt d.c. source is connected across the combination. Then power consumed by each bulb is
In a neon discharge tube 2.9 × 10 18 N e + ions move to the right each second while 1.2 × 10 18 electrons move to the left per second. Electron charge is 1.6 × 10 − 19 C . The current in the discharge tube
The resistance of a conductor is 5 ohm at 50 0 C and 6 ohm at 100 0 C. Its resistance at 0 0 C is
A copper wire of length 1 m and radius 1 mm is joined in series with an iron wire of length Z m and radius 3 mm and a current is passed through the wires. The ratio of the current density in the copper and iron wires is
Following figure shows cross-sections through three long conductors of the, same length and material, with square cross-section of edge lengths as shown. Conductor B will fit snugly within conductor A, and conductor C will fit snugly within conductor B. Relationship between their end to end resistance is
A battery of emf E is connected across a conductor as shown. As one observes from A to B, Column-I Column-II (i) current (p) increases (ii) drift velocity of electron (q) decreases (iii) electric field (r) remains same (iv) potential drop per unit length (s) cannot be determined Now, match the given columns and select the correct option from the codes given below.
In the circuit shown, each cell has as emf of 5 volt and internal resistance 1Ω. Then potential difference between B and A is
Two cylindrical rods of uniform cross-sectional area A and 2A, having free electrons per unit volume 2n and n respectively are joined in series. A current I flows through them in steady state. Then the ratio of drift velocity of free electrons v L in left rod to drift velocity of electrons in the right rod v R is
Two resistors of resistances R 1 and R 2 having R 1 > R 2 arc connected in parallel. For equivalent resistance R, the correct statement is
Four identical bulbs are connected to a battery as shown in the figure. After the switch S is closed,
The equivalent resistance of a group of resistances is R. If another resistance is connected in parallel to the group, its new equivalent becomes R 1 and if it is connected in series to the group, it new equivalent becomes R 2 . Then
Three resistances of, 1 Ω each are connected in parallel. Such connection is again connected with 2 / 3 Ω resistor in series. The resultant resistance will be
Two resistances are joined in parallel whose resultant is 6 8 ohm. One of the resistance wires is broken and the effective resistance becomes 2 Ω Then the resistance in ohm of the wire that got broken was
Given three equal resistors. How many different combination of all the three resistors can be made?
The resistance of all the wires between any two adjacent dots is R. The equivalent resistance between A and.B as shown in figure is
In the network shown, when switch S is open balancing length AN 1 = 60 cm and when the switch S is closed, balancing length AN 2 = 50 cm. then the value of r is
Two identical cells send the same current in 2 Ω resistance, whether connected in series or in parallel. The internal resistance of the cell should be
Two sources of emf 6 V and internal resistance 3 Ω and 2 Ω are connected to an external resistance R as shown. If potential difference across battery A is zero, then value of R is
A battery of e.m.f. 10 V is connected to resistance as shown in figure. The potential difference V A − V B the points A and B is
Four resistances are connected in a circuit as shown in the given figure. The electric current flowing through 4 ohm and 6 ohm resistance, respectively, are
In the network shown, the potential difference between A and B is R = r 1 = r 2 = r 3 = 1 Ω , E 1 = 3 V , E 2 = 2 V , E 3 = 1 V
N identical cells, each of emf E and internal resistance r are joined in series. Out of N cells, n cells are wrongly connected i.e., their terminals are connected in reverse of that required for series connection n < N 2 . Let E 0 be the emf of resulting battery and r 0 be its internal resistance. Then
In the circuit shown below, the cell has an e.m.f. of 10 V and internal resistance of 1 Ω . The other resistances are shown in the figure. The potential difference V A − V B is
A uniform wire of resistance 9 Q is cut into 3 equal parts. They are connected in the form of equilateral triangle ABC. A cell of e.m.f. 2 V and negligible internal resistance is connected across B and C. Potential difference across AB is
The potential drop across the 3 Ω resistor is
In circuit shown below, the resistances are given in ohms and the battery is assumed ideal with emf equal to 3 volt. The voltage across the resistance R 4 is
Two batteries of e.m.f. 4 V and 8 V with internal resistances 1 Ω and 2 Ω are connected in a circuit with a resistance of 9 Ω as shown in figure. The current and potential difference between the points P and Q are
In the circuit given in figure below, the current through 12 Ω resistor will be
In the given network, the potential at point O is (Given V 0 − V S = 18 V )
In the circuit shown here, E 1 = E 2 = E 3 = 2 V and R 1 and R 2 = 4 ohms . The current flowing between points A and B through battery E 2 is
In the circuit shown, calculate the current through 6 V battery.
Permissible current through a fuse wire of diameter 1 mm is 1A. What should be the radius of a fuse wire, made of same material, whose permissible current is 8A ?
In the circuit shown if point O is earthed, the potential of point X is equal to
In the circuit shown, reading of ammeter and voltmeter are respectively.
In the figure shown, the capacity of the condenser C is 2 μ F . If the circuit is in steady state, the current in 2 Ω resistor is
In the circuit shown, the currents in 4 Ω and 8 Ω resistances are
In the circuit shown power dissipated in R just after S is closed is P 1 and a long time after S is closed power dissipated in R is P 2 . Then
In the network shown, potential of point C is
In the given circuit, the ratio of voltmeter reading to the ammeter reading is R’. If resistance of ammeter is R A , and that of voltmeter R V , then
In the circuit shown in the figure, if switches S 1 and S 2 have been closed for a long time, then charge on the capacitor
In the circuit shown, switch S is closed at t = 0. Let i 1 and i 2 be the currents at any finite time t, then the ratio i 1 i 2 .
A galvanometer can be converted into an ammeter by connecting
A cell of internal resistance 1.5 Ω and of emf 1.5 volt balances 500 cm on a potentiometer wire. If a wire of 15 Ω is connected between the balance point and the cell, then the balance point will shift
A 100 V voltmeter of internal resistance 20 k Ω in series with a high resistance R is connected to a 110 V line. If the voltmeter reads 5 V the value of R is
Seven resistances are connected as shown in the figure. The equivalent resistance between A and B is
In meter bridge or Wheatstone bridge for measurement of resistance, the known and the unknown resistances are interchanged. The error so removed is
For measurement of potential difference, potentiometer is preferred in comparison to voltmeter because
In the given circuit, the galvanometer G will show zero deflection if
Two cells when connected in series are balanced on 8 m on a potentiometer. If the cells are connected with polarities of one of the cells is reversed, they balance on 2 m. The ratio of e.m.f.’s of the two cells is
It is required to measure equivalent resistance of circuit with ideal battery ideal voltmeter and ideal ammeter. Which circuit diagram shows voltmeter V and ammeter A correctly positioned to measure the total resistance of circuit?
In Wheatstone’s bridge, P = 9 Ω , Q = 11 Ω , R = 4 Ω and S = 6 Ω . How much resistance must be put in parallel to the resistance S to balance the bridge?
In the shown arrangement of the experiment of the meter bridge, if AC corresponding to null deflection of galvanometer is x, what would be its value if the radius of the wire AB is doubled?
A potentiometer having the potential gradient of 2 mV/cm is used to measure the difference of potential across a resistance of 10 ohm. If a length of 50 cm of the potentiometer wire is required to get the null point, the current passing through the 10 ohm resistor is (in mA)
In a potentiometer experiment, it is found that no current passes through the galvanometer when the terminals of the cell are connected across 0.52 m of the potentiometer wire. If the cell is shunted by a resistance of 5 Ω , balance is obtained when the cell is connected across 0.4 m of the wire. Find the internal resistance of the cell.
In the circuit shown in figure, XY is a potentiometer wire 100 cm long. The circuit is connected as shown. With switches S 2 and S 3 open, a balance point is found at Z. After switch ,S 1 has remained closed for some time, it is found that contact at Z must be moved towards Y to maintain a balance. Which of the following is most likely reason for this?
The circuit shown here is used to compare the e.m.f. of two cells E 1 and E 2 (E 1 > E 2 ). The null point is at C when the galvanometer is connected to E 1 . When the galvanometer is connected to E 2 , the null point will be
In the potentiometer arrangement shown, the driving cell A has emf ε and internal resistance r. The emf of the cell B is ε 2 and internal resistance 2r. The potentiometer wire CD is 100 cm long. If balance is obtained with length CJ = l , then
Resistances in the two gaps of a meter bridge are l0 ohm and 30 ohm, respectively. If the resistances are interchanged the balance point shifts by
In a potentiometer experiment, the galvanometer shows no deflection when a cell is connected across 60 cm of the potentiometer wire. If the cell is shunted by a resistance of 6 Ω the balance is obtained across 50 cm of the wire. The internal resistance of the cell is
The length of a wire of a potentiometer is 100 cm, and the e.m.f. of its standard cell is E volt. It is employed to measure the e.m.f. of a battery whose internal resistance is 0.5 Ω . If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is
Two electric bulbs rated P 1 watt V volts and P 2 watt V volts are connected in parallel and V volts are applied to it. The total Power will be
E denotes electric field in a uniform conductor, I corresponding current through it, v d drift velocity of electrons and P denotes thermal power produced in the conductor, then which of the following graph is incorrect?
In the circuit diagram, all the bulbs are identical. Which bulb will be the brightest?
What is the ratio of heat generated in R and 2R?
There are two electric bulbs of 40 W and 100 W. Which one will be brighter when connected in series and when in parallel?
An electric kettle has two heating coils. When one coil is used, water in the kettle boils in 5 minutes, while when second coil is used, same water boils in 10 minutes. If the two coils, connected in parallel, are used simultaneously, the same water will boil in time
If the length of the filament of a heater is reduced by 10%, the power of the heater will
Water boils in an electric kettle in 15 minutes after switching on. If the length of the heating wire is decreased to 2/3 of its initial value, then the same amount of water will boil with the same supply voltage in
The resistance of an electrolyte varies with temperature T as R T = R 0 1 + αT , where R 0 and α are constants. A constant potential difference V is applied to the two electrodes (each of surface area A) which are dipped in this electrolyte. If T 0 it the temperature of the surroundings, the loss of heat to the surroundings per unit surface area per unit time is governed by the same relation H = k T − T 0 A , then the steady state temperature is
A triangle is constructed using wires AB, BC and CA of same material and of resistance α , 2 α a n d 3 α , respectively. Another wire of resistance α / 3 from A can make a sliding contact with wire BC. Find the maximum resistance of the network between points A and the point of sliding wire with BC.
In the circuit shown, the variable resistance X is to be adjusted such that the ideal ammeter reads the same in both the positions of the key, when connected independently to 1 and then to 2. The reading of the ammeter is 2 A. If E = 10 V then X is
Two heating coils, one of fine wire and the other of thick wire made of same material and of same length are first connected in series and then in parallel. Which of the following statements is correct?
A battery of e.m.f. 10 V and internal resistance 0.5 ohm is connected across a variable resistance R. The value of R for which the power delivered in it is maximum is given by
The potential difference in open circuit for a cell is 2.2 volts. When a 4 ohm resistor is connected between its two electrodes the potential difference becomes 2 volts. The internal resistance of the cell will be
Electric bulbs 50 W-100 V glowing at full power are to be used in parallel with battery 120 V, 10 Ω . Maximum number of bulbs that can be connected so that they glow in fulI power is
Five equal resistances, each of resistance R, are connected as shown in the figure. A battery of V volts is connected between A and B. The current flowing in AFCEB will be
Three resistances P, Q, R each of 2 Ω and an unknown resistance S form the four arms of a Wheatstone’s bridge circuit. When a resistance of 6 Ω is connected in parallel to s the bridge gets balanced. what is the value of S?
See the electrical circuit shown in this figure. Which of the following equations is the correct equation for it?
The internal resistance of a cell is the resistance of
Statement 1: Electric field outside the conducting wire which carries a constant current is zero. Statement 2: Net charge on conducting wire is zero.
Statement 1: In practical application, power rating of resistance is not important. Statement 2: Property of resistance remains same even at high temperature.
Statement 1: In a simple battery circuit, the point of lowest potential is positive terminal of the battery. Statement 2: The current flows towards the point of the higher potential as it flows in such a circuit from the negative to the positive terminal.
Statement 1: Electric appliances with metallic body, e.g. heaters, presses etc, have three pin connections, whereas an electric bulb has a two pin connection. Statement 2: Three pin connections reduces heating of connecting cables.
Statement 1: A potentiometer of longer length is used for accurate measurement. Statement 2: The potential gradient for a potentiometer of longer length with a given source of e.m.f. becomes small.
If an ammeter is to be used in place of a voltmeter, then we must connect with the ammeter a
Consider two identical cells each of emf E and internal resistance r connected to a load resistance R. Column I Column II i. Maximum power transfer to load if cells are connected in series p. E 2 4 r ii. Maximum power transfer to load if cells are connected in parallel q. E 2 2 r iii. For series connection of cells r. E eq = E , r eq = r 2 iv. For parallel connection of cells s. E eq = 2 E , r eq = 2r Now, match the given columns and select the correct option from the codes given below.
A wire of resistance R is divided in 10 equal parts. These parts are connected in parallel. The equivalent resistance of such connection will be
Kirchhoff’s first law i.e., ∑ i = 0 at a junction is based on the law of conservation of
Thirteen resistances each of resistance R are connected in the circuit as shown in the figure below. The effective resistance between A and B is
A storage battery is connected to a charger for charging with a voltage of 12.5 volts. The internal resistance of the storage battery is 1 Ω When the charging current is 0.5 A, the emf of the storage battery is
Three resistors each of 4 Ω are connected together to form a network. The equivalent resistance of the network cannot be
In the circuit shown, switch S 2 is closed first and is kept closed for a long time. Now S 1 is closed. Just after that instant, the current through S 1 is
For what value of R in circuit, current through 4 Ω resistance is zero?
A voltmeter with resistance 500 Ω is used to measure the emf of a cell of internal resistance 4 Ω . The percentage error in the reading of the voltmeter will be
A cell of emf E has an internal resistance r and is connected to a rheostat. When resistance R of rheostat is changed, correct graph of potential difference across it is
A candidate connects a moving coil voltmeter V, a moving coil ammeter A and a resistance R as shown in figure. If the voltmeter reads 20 Y and the ammeter reads 4 A, R is
What is the reading of voltmeter in the following figure?
50 Ω a n d 100 Ω resistors are connected in series. This connection is connected with a battery of 2.4 volts. When a voltmeter of 100 Ω resistance is connected across 100 Ω resistor, then the reading of the voltmeter will be
The potential difference across the 100 Ω resistance in the following circuit is measured by a voltmeter of 900 Ω resistance. The percentage error made in reading the potential difference is
If the ammeter in the given circuit reads 2 A,the resistance R is
A galvanometer has a resistance of 25 Ω and a maximum of 0.01 A current can be passed through it. In order to change it into an ammeter of range 10 A, the shunt resistance required is
In the given circuit diagram, potential difference across 2 Ω resistance is
If in the experiment of Wheatstone’s bridge, the positions of cells and galvanometer are interchanged, then balance points will
In the figure given, the value of X resistance when the potential differences between B and D is zero, is
When electric bulbs of same power, but different marked voltage are connected in series across the power line, their brightness will be
A resistor R 1 dissipates the power P when connected to a certain generator. If the resistor R 2 is put in series with R 1 , the power dissipated by R 1
Two resistances are connected in two gaps of a metre bridge. The balance point is 20 cm from the zero end. A resistance of 15 ohms is connected in series with the smaller of the two. The null point shifts to 40 cm. The value of the smaller resistance in ohms is
AB is a wire of uniform resistance. The galvanometer G shows no current when the length AC = 20 cm and CB = 80 cm. The resistance R is equal to
n cells of emfs E 1 , E 2 …………, E n , and internal resistance r 1 , r 2 ……………… r n are in series to form closed circuit with zero external resistance. For each cell ratio of emf to internal resistance is K then current in circuit is:
The resistance of a wire is 5 ohm at 50°C and 6 ohm at 100°C. The resistance of the wire at 0°C will be
The temperature coefficient of resistance of a wire is .00125°C -1 . At 300 K its resistance is one ohm. The asistance of the wire will be 2 ohm at
In an experiment to measure the internal resistance of a cell, by a potentiometer, it is found that the balance point is at a length of 2 m, when the cell is shunted by a 5 resistance and is at a length of 3 m when the cell is shunted by a 10 Ω resistance. The internal resistance of the cell is then
Five resistances are connected as shown in fig. The effective resistance between the points A and B is
A wire has a resistance 10 Ω . It is stretched by one-tenth of its original length. Then its resistance will be
The ring shown in fig. has zero resistance. The equivalent resistance between points A and B will be
In a potentiometer experiment, it is found that no current passes through the galvanometer when the terminals of the cell are connected across 52 cm of the potentiometer wire. If the cell is shunted by a resistance 5 Ω , the balance point is found at 40 cm of the wire from the same end. The internal resistance of the cell is
For what value of unknown resistance X, the potential difference between B and D will be zero in the arrangement of fig.
Resistances of 1, 2 and 3 ohm are connected in the form of a triangle. If a 1.5 volt cell of negligible internal resistance is connected across the 3 ohm resistor, the current flowing through this resistance will be
An Edison cell and a Iead accumulator when placed in series produce a null deflection at a distance 204 cm in a potentiometer. But when placed in opposition produces null deflection. at a distance of 36 cm. If the e.m.f. of Edison cell is 1 . 4 V, the e.m.f. of lead accumulator is
For the network shown in fig, the value of n current is
In a potentiometer experiment, the balance with a cell is at length 240 cm. On shunting the cell with a resistance of 2 Ω , the balancing length becomes 120 cm. The internal resistance of the cell is.
A battery consists of variable number (n) of identical cells having internal resistance r each. They are connected in series. The terminals of battery are short-circuited and current is measured. Which of the graphs [Fig] gives correct relationship between i and n
For the post office box arran8ement to determine the value of unknown resistance, the unknown resistance should be connected between
Six equal resistances are connected between point P, Q and R as shown in the fig. Then the net resistance will be maximum between
In a metre bridge experiment null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X <Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4 X against Y?
A cube is constructed from 12 identical wires. Current enters one corner of the cube and it leaves the opposite corner. If the resistance of each wire is r, then equivalent resistance will be
A battery consists of a variable number n of identical cells having internal resistance r each. They are connected in series. The terminals of the battery are short circuited and the current i is measured. Which of the graphs [fig] gives correct relationship between i and n?
In the circuit shown in fig. E, F, G and H are cells of e.m.f. 2, 1, 3 and 1 volt and their internal resistances are 2, 7,3 and 1 ohm respectively. The potential difference between B and D is
In the given circuit [fig] potential difference across the capacitor must be
In the given circuit of fig.no current is passing through the galvanometer connected to a meter bridge. Distance AC corresponding to null deflection of galvanometer is x. What would be its value if the radius of the wire AB is doubled ?
A (100 W, 200 V) bulb is connected to a 160 volts supply. The power consumption would be
Three 60 W, 120 V light bulbs are connected across 12o V power line as shown in fig. The total power dissipated in the three bulbs is
Fig. shows three similar lamps L 1 , L 2 , and L 3 connected across a power supply. If the lamp L 3 . fuses, how will the light emitted by L 1 , and L 2 , change ?
Resistances R 1 , and R 2 , are joined in parallel and a current is passed so that the amount of heat liberated is H 1 and H 2 , respectively. The ratio of H 1 / H 2 , has the value
Time taken by a 896 W heater to heat one litre of water from 10°C to 40°C is
A coil is embedded in a block of ice placed in an insulator box. If a current of1 . 0 amp is passed through the coil by applying a potential difference of 210 V across it, the amount of ice melted in one hour is
Masses of three wires are in the ratio 1:3:5. Their lengths are in the ratio 5:3:1. When connected in series with a battery, the ratio of heat produced in them will be
How many 60 watt lamps may be safely run on a 230 volt circuit fitted with 5 amp fuse ?
A22O volt,7000 watt bulb is connected across a 110 volt mains supply. The power consumed will be
A constant voltage is applied between the two ends of a uniform metallic wire. Same heat is developed in it. The heat developed is doubled if
A fuse wire with a circular cross-sectional radius of 0.02 mm blows with a current of 5 ampere. For what current, another fuse wire made from the same material with cross-sectional radius of 0.04 m wiII blow ?
A cell sends a current through a resistance R 1 , for one second and then sends current through another resistance R 2 for one second. Same heat is produced in both the resistances. The internal resistance of the cell is
n identical light bulbs, each designed to draw P power from a certain supply, are joined in series across that supply. The total power which they will draw is
Three equal resistances each of 10 Ω are connected as shown in the fig. The maximum power consumed by each resistor is 20 W. Then maximum power consumed by the combination is
A cell of internal resistance r drives a current through an external resistance R. The power delivered by the cell to the external resistance is maximum when
An electric bulb is designed to draw P o power at V o voltage, If the voltage is V, it draws P power. Then
A 100 W bulb B 1 , and two 60 W bulbs B 2 and B 3 , are connected to a 250 V source as shown in fig. Now W 1 ,W 2 , and W 3 are the output powers of the bulbs B 1 ,B 2 and B 3 , respectively. Then
Three equal resistances each of R ohm are connected as shown in fig. A battery of 2 V and internal resistance 0 .1 ohm is connected across the circuit. The value of R for which the heat generated in the circuit will be maximum is
A” B, C are identical bulbs. How does the brightness of A and B change when the switch S is closed ?
ln the circuit shown in fig. the total power drawn from the battery is
In the arrangement shown in the figure when the switch S 2 is open, the galvanometer shows no deflection for l = L/2. When the switch S 2 is closed, the galvanometer shows no deflection for l = 5 12 L . The internal resistance (r) of 6 V cell, and the emf E of the other battery are respectively
In the circuit shown in the figure, reading of voltmeter is V 1 when only S 1 is closed, reading of voltmeter is V 2 when only S 2 is closed and reading of voltmeter is V 3 when both S 1 and S 2 are closed. Then,
The power supplied by battery shown in the diagram is (ammeter is ideal)
A wire of length L and of 3 identical cells of negligible internal resistance are connected in series. Due to the current, temperature of wire rises Δ T in time t. A number of N similar cells is now connected in series with a wire of same material and cros-section but length 2 L. The temperature of wire is raised by same amount Δ T in same time t. Find the value of N
A set of n equal resistors, of value R each, are connected in series to a battery of emf E and internal resistance R . The current drawn is I . Now, the n resistors are connected in parallel to the same battery. Then the current drawn from battery becomes 10 I . The value of n is
A battery consists of a variable number n of identical cells (having internal resistance r each) which are connected in series. The terminals of the battery are short-circuited and the current I is measured. Which of the graphs shows the correct relationship between I and n ?
A carbon resistor of ( 47 ± 4 . 7 ) k Ω is to be marked with rings of different colours for its identification. The colour code sequence will be
A potentiometer wire is 100 c m long and a constant potential difference is maintained across it. Two cells are connected in series first to support one another and then in opposite direction. The balance points are obtained at 50 c m and 10 c m from the positive end of the wire in the two cases. The ratio of emf’s is
Two cities are 150 km apart. Electric power is sent from one city to another city through copper wires. The fall of potential per km is 8 volt and the average resistance per km is 0.5 Ω . The power loss in the wire is
The resistances in the two arms of the meter bridge are 5 Ω and R Ω respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6 l 1 .The resistance R is
A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of 2.0 V and a negligible internal resistance. The potentiometer wire itself is 4 m long. When the resistance R, connected across the given cell, has values of (i) infinity (ii) 9.5 Ω the balancing lengths on the potentiometer wire are found to be 3 m and 2.85 m, respectively. The value of internal resistance of the cell is
In the circuit when switch S 1 is closed and S 2 is open, the ideal voltmeter shows a reading 18V. When switch S 2 is closed and S 1 is open, the reading of voltmeter 24V. When S 1 and S 2 both are closed the voltmeter reading will be
When the key K is pressed at time t=0 , which of the following statements about the current I in the resistor AB of the given circuit is true
The charge flowing through a resistance R varies with time t as Q = a t – b t 2 where a and b are positive constants. The total heat produced in R is
Which of the following acts as a circuit protection device?
In a potentio meter experiment, the balancing length with a cell is at a length of 240 cm. On shunting the cell with a resistance of 2 Ω , the balancing length becomes 120cm. The internal resistance of the cell is:
When the switch is closed, then initial current through 1 Ω resistor is (see figure)
Two metal wires of identical dimensions are connected in series. If σ 1 a n d σ 2 are the conductivities of the metal wires respectively, the effective conductivity of the combination is
A potentiometer wire of length L and a resistance r are connected in series with a battery of e.m.f. E 0 and a resistance r 1 . An unknown e.m.f. E is balanced at a length l of the potentiometer wire. The e.m.f. E will be given by
The resistances of the four arms P, Q, Rand Sin a Wheatstone’s bridge are 10 ohm, 30 ohm, 30 ohm and 90 ohm, respectively. The e.m.f. and internal resistance of the cell are 7 volt and 5 ohm respectively. 1f the galvanometer resistance is 50 ohm, the current drawn from the cell will be
The internal resistance of a 2.1 V cell which gives a current of 0.2 A through a resistance of 10 Ω is
A wire of resistance 4 Ω is stretched to twice its original length. The resistance of stretched wire would be
In the circuit shown in figure, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistance of resistor R will be
A capacitor C is connected to the two equal resistances as shown in figure. What is the ratio of the time constants during charging and discharging of the capacitor?
A, B and C are voltmeters of resistance R, 1.5R and 3 R respectively as shown in the figure. When some potential difference is applied between X and Y, the voltmeter readings are V A , V B and V C respectively. Then
A filament bulb 500 W , 100 V is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W . The value of R is
Two rods are joined end to end, as shown. Both have a crosssectional area of 0 . 01 c m 2 . Each is 1 meter long. One rod is of copper with a resistivity of 1 . 7 × 10 – 6 ohm-centimeter, the other is of iron with a resistivity of 10 – 5 ohm-centimeter. How much voltage is required to produce a current of 1 ampere in the rods?
If the balance point is obtained at the 25 t h cm in a metre bridge the resistances in the left and right gaps are in the ratio of
A carbon resistor has colour strips as violet, yellow brown and golden. The resistance is
A battery is connected to a uniform resistance wire AB and B is earthed. Which one of the graphs below shows how the current density J varies along AB
Across a metallic conductor of non-uniform cross section a constant potential difference is applied. The quantity which remains constant along the conductor is
A potentiometer wire has length 4 m and resistance 8 Ω . The resistance that must be connected in series with the wire and an accumulator of e.m.f. 2V, so as to get a potential gradient 1mV per cm on the wire is
A 12 cm wire is given a shape of a right angled triangle A B C having sides 3 cm, 4 cm and 5 cm as shown in the figure. The resistance between two ends (A B, BC, CA) of the respective sides are measured one by one by a multi-meter. The resistances will be in the ratio
The resistance of a wire is ‘R’ ohm. If it is melted and stretched to ‘n’ times its original length, its new resistance will be
A potentiometer is an accurate and versatile device to make electrical measurements of EMF because the method involves
Which of the following graph represents the variation of resistivity ( ρ ) with temperature (T) for copper?
The color code of a resistance is given below : The values of resistance and tolerance, respectively, are :
A resistance wire connected in the left gap of a meter bridge balances a 10 Ω resistance in the right gap at a point which divides the bridge wire in the ratio 3 : 2. If the length of the resistance wire is 1.5 m, then the length of 1 Ω of the resistance wire is :
A charged particle having drift velocity of 7 .5 × 10 − 4 m s − 1 in an electric field of 3 × 10 − 10 Vm − 1 , has a mobility in m 2 V − 1 s − 1 of
For the circuit shown in the figure, the current I will be
The equivalent resistance between A and B for the mesh shown in the figure is
Two solid conductors are made up of same material, have same length and same resistance. One of them has a circular cross section of area A 1 and the other one has asquare cross section of area A 2 . The ratio A 1 / A 2 is
For the circuit given below, the Kirchoff’s loop rule for the loop BCDEB is given by the equation
The emf and internal resistance of the battery shown in figure are 4.3 V and 1 Ω respectively. The external resistance R is 50 Ω . The resistance of the voltmeter and ammeter are 200 Ω and 2 Ω respectively. Find the readings of the two meters.
The e.m.f. of the driver cell of a potentiometer is 2V and its internal resistance is negligible. The length of the potentiometer wire is 100 cm and resistance is 5 Ω . How much resistance is to be connected in series with the potentiometer wire to have a potential gradient of 0 . 05 m v c m – 1
A potential difference V is applied to a copper wire of length l and thickness d. If V is doubled, the drift velocity.
A wire has resistance of 24 Ω is bent in the following shape. The effective resistance between A and B is
Following figure shows four situations in which positive and negative charges moves horizontally through a region and gives the rate at which each charge moves. Rank the situations according to the effective current through the region greatest first
A carbon resistor has colour strips as orange, red brown and red. The resistance is
A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be
A galvanometer together with an unknown resistance in series is connected across two identical batteries each of 1.5 V. When the batteries are connected in series, the galvanometer records a current of 1A, and when the batteries are in parallel, the current is 0.6 A. What is the internal resistance of the battery ?
A cell of emf E and internal resistance ‘ r’ is connected to a variable external resistor ‘R’. The graph which gives the terminal voltage of cell ‘V’ with respect to R is :
If power dissipated in 1 Ω resistor is 16 watt., total power consumed by the network between A and B is
For the shown cylindrical conductor AB, connected across a source of emf, resistivity of the material decreases as we move from end A towards end B. As we move from end A towards end B
In the circuit shown, if v a − v b = 10 v o l t , find ‘r’
The potential difference between A & B is
There are 45 number of cells with internal resistance of each cell is 0 .5 Ω . To get the maximum current through a resistance of 2 .5 Ω , one can use m rows of cells, each row having n cells. The values of m and n are
The V – I graph for a conductor at temperature T 1 and T 2 are as shown in figure. Then ( T 2 – T 1 ) is equal to [ α = temperature coefficient of resistivity]
A circuit element is placed in a closed box. At time t = 0, a constant current generator supplying a current of 1A is connected across the box. Potential difference across the box varies according to the graph shown in figure. The element in the box is
A galvanometer of resistance 2 Ω and having full scale deflection for a current of 100 mA can be converted into a voltmeter of range 5 V by connecting a resistance R in series with the galvanometer. The resistance R in ohm is :
Thirteen resistances, each of resistance R ohm, are connected in the circuit as shown in figure. The effective resistance between A and B is
When a potential difference is applied across a cylindrical wire, average drift speed of free electrons is ‘V’. Now the wire is stretched to two times its original length and same potential difference is applied across it. Then the new drift speed of free electrons will be
In the following circuit E 1 = 12 volt and zero internal resistance while the battery E 2 = 2 volt and also has zero internal resistance. If the reading of galvanometer is zero, the value of resistance ‘X’ in ohm is
A thin uniform wire of resistance R is bent in the form of a regular polygon of n sides( n ≥ 3 ). The equivalent resistance between two adjacent vertices of the polygon is
An 80W galvanometer deflects full-scale for a potential of 20 mV. A voltmeter deflecting full-scale of 5 V is to be made using this galvanometer. We must connect
Figure shows three similar lamps P,Q and R connected across a power supply. If the lamp R fuses, how will the light emitted by P and Q change?
Four resistors are connected as shown in following figure. A 6V battery of negligible resistance is connected across terminals A and C. The potential difference across terminals B and D will be
In the circuit element shown here, if the potential at point B, V B = 0 , then the potentials of A and D are given as
In the circuit shown in the adjoining figure, the bridge is balanced, the unknown resistance is of
The length of a potentiometer wire is l. A cell of emf E is balanced at a length l/3 from the positive end of the wire. If the length of the wire is increases by l 2 . At what distance will the same cell give a balanced point
N identical cells are connected to form a battery. When the terminals of the battery are joined directly (short-circuited), current I flows in the circuit. To obtain the maximum value of I,
The temperature coefficient of resistance of conductor varies as α T = 3 T 2 + 2 T .If R 0 is resistance at T = 0 and R is resistance at T, then
The e.m.f. of the driver cell of a potentiometer is 2V and its internal resistance is negligible. The length of the potentiometer wire is 100 cm and resistance is 5 ohms. How much resistance is to be connected in series with the potentiometer wire to have a potential gradient of 0.05 m V c m – 1 ?
In the circuit shown in fig. the rate of heat produced in the 5 ohm resistor is 20 J s – 1
If a copper wire is stretched to make its radius decrease by 0.1%, then percentage increase in resistance is approximately
How will the reading in the ammeter A of Fig. be affected if another identical bulb Q is connected in parallel to P as shown. The voltage in the mains is maintained at a constant value.
A galvanometer has a resistance of 3663 Ω . A shunt S is connected across it such that 1/34 of the total current passes through the galvanometer. The value of the shunt is
Two cells of emfs E 1 and E 2 are connected as shown in figure ( E 1 > E 2 ) , when a potentiometer is connected between A and B, balancing length of the potentiometer wire is 300 cm. On connecting the same potentiometer between A and C, the balancing length is 100 cm. The ratio E 1 / E 2 is
In the diagram shown, reading of the ammeter just after closing the switch S is 12 A and a long time after S is closed is 4 A. Then value of ‘R’ is
Two filament bulbs A and B are connected in series combination. Filament of A is made of carbon and that of B is made of platinum. At t=0, the combination is connected to a d.c. source. Then after a long time
48 cells each of internal resistance 1 Ω are arranged in a mixed combination and the combination is connected across a resistor of resistance 3 Ω . Number of cells in each row is n and number of rows is m if maximum current flows through the 3 Ω resistor, then
The magnitude of current in the middle branch in ampere unit is
A wire is connected to a battery and drift velocity of electrons in the conductor is v 0 . If wire is stretched to quadruple its length and connected to same battery, the new drift velocity is
A cell can be balanced against 110 cm and 100 cm of potentiometer wire, respectively with and without being short circuited through a resistance of 10 ohm. Its internal resistance is
A platinum resistance thermometer reads 0 0 C when its resistance is 80Ω and 100 0 C when its resistance is 90Ω. Find the temperature at the platinum scale at which the resistance is 86Ω
In the network shown, the equivalent resistance between A and B is
In the network shown in figure power dissipated in 2 Ω and 6 Ω resistors are P 1 and P 2 respectively. Then P 1 P 2 is
If the d.c. voltage applied across a bulb increases by 2% and the resistance of its filament increases by 1% what is the maximum change in power dissipated in the bulb?
A steady current is flowing through the conductor of variable cross section as shown in the figure. Then select the correct option.
A 1 µA beam of protons with a cross-sectional area of 0.5 sq. mm is moving with a velocity of 3 x 10 4 ms – 1 . Then charge density of beam is
Potential difference between the ends of a current carrying conductor of length 50 cm is 10 volt. If the drift velocity of free electrons in the conductor is 8 × 10 − 5 m / s , find the mobility of electrons in m 2 V − 1 S − 1 .
Which of the following graphs represents the variation of resistivity with temperature for carbon?
Two electric bulbs each of rating 60 W, 200 V are connected in series and a 100 volt d.c. supply is connected across the combination. Then total power consumed by the combination is
Resistance of an ammeter is 4 Ω and its range is 0 to 2 A. What shunt resistance should be used to increase its range from 0 to 8 A?
In the circuit shown in figure, the resistance R can be varied. By changing R power dissipated in it is made maximum. If the emf of the battery is 10 volt and internal resistance is 1 ohm then find the maximum power dissipated in R.
In a potentiometer, the balancing length of a cell of emf 10 volt is 120 cm. What will be the balancing length of potentiometer wire for a 8 volt cell?
In the network shown, current flowing through the 8 volt cell is
Two ends of a metallic wire of uniform cross section are connected to the terminals of a battery. Drift velocity of free electrons is found to be V. If the length of the wire is doubled and cross sectional area is halved, drift velocity of free electrons will be
A 5 watt, 10 volt bulb is connected to a cell of emf 10 volt and internal resistance 5 Ω . Then power consumed by the bulb is
Balancing length of a potentiometer wire of a cell of emf 20 volt is 80 cm. What will be the balancing length of a cell of emf 15 volt in the same potentiometer wire?
Permissible current in a fuse wire of radius 0.1 mm is 2A. What is the permissible current in a fuse wire of radius 0.4 mm?
In the network shown, potential of point A is
A cell of emf 10 volt and internal resistance 2 Ω gives a null point in a potentiometer and the balancing length is found to be 55 cm. Now the cell is short circuited through an external resistance. R and the balancing length is found to be 50 cm then the value of R is
Assuming that the electronic charge is 1 . 6 x 10 – 19 coulombs, the number of electrons passing through a section of wire per sec, when the wire carries a current of one ampere is :
A current of 4.8 A is flowing in a conductor. The number of electrons passing per sec through the conductor will be :
In the Bohr’s model of hydrogen atom the electron moves around the nucleus in a circular orbit of radius 5 x 10 – 11 m with time period 1 . 5 x 10 – 16 s . The current associated with the electron motion is :
A capacitor of 10 μF is charged to a potential difference of 20 V. If it is discharged in 0.2 s, the average current during discharging is :
A current of 10 amperes is maintained in a conductor of cross-section of 10 – 4 m 2 . If the electron density is 9 x 10 28 m – 3 , what is the drift velocity of free electrons ?
Electric current through a conductor varies with time as l ( t ) = 50 sin ( 100 πt ) . Here I is in amperes and t in seconds. Total charge that passes any point from t = 0 to t = 1 200 sec is :
A storage ring of radius 45 m at a high energy accelerator has a 18A circulating beam of electrons. The electrons are moving so fast that their speed can be taken as 3 x 10 8 m / s with an insignificant error. Number of electrons in the beam is :
A negligibly small current is passed through a wire of length 15 m and uniform cross-section 6 . 0 x 10 – 7 m 2 . The measured resistance of the wire is 5.0 Ω . The resistivity of the material is :
The Fig. 4.58 represents the V-I characteristics of a circuit element. The dynamic resistance in the region AB is :
A potential difference, applied between the ends of a conductor of uniform radius 2 mm, results in an electric field 300 V/m along the length of conductor. If current in the conductor is 4 A, resistivity of the material of conductor is nearly :
A technician has only two resistance coils. By using them singly, in series or in parallel, he is able to obtain the resistance of 3, 4, 12 and 16 Ω . What are the resistances of the two coils?
A battery and resistances are connected in a circuit as follows. The current flowing through the ammeter A is :
A wire (10 cm)h as resistance 12 Ω . It is bent in the form of a circle. The effective resistance between the two points of any diameter is equal to :
Ten identical electric bulbs, each rated 220 V, 50 W are used in parallel on 220 V line for 10 hours per day in a month of 30 days .T he electric energy consumed in kilo watt hours is :
If a steady current I is flowing through a cylindrical element ABC. Choose the correct relationship :
In shown circuit, initially capacitor is uncharged. If switch S is closed at t = 0, then initial current through R is :
In the given circuit, with steady state, the potential difference across the capacitor must be :
A 4 μFcapacitor and a resistance of 2.5 M Ω are in series with 12V battery. Find the time after which the potential difference across the capacitor is 3 times the potential difference across the resistor :
A charged capacitor of capacitance C and having charge Q is to be connected with another uncharged capacitor of capacitance C 1 through a resistor R as shown in figure. The value of C 1 for heat liberated in R to be minimum is :
The figure shows a graph of current (I) flowing through a cell against its terminal voltage (V). The emf and internal resistance of this cell are :
In the circuit shown in Fig, the ammeter reads a current :
In the part of a circuit shown in Fig, the potential difference between points G and H ( V G – V H ) will be :
In the circuit shown in Fig. 5.178, the voltmeter reading would be : (A and V are ideal ammeter and voltmeter respectively)
In Fig, AB is a wire of length 100 cm whose resistance is 5 Ω . If galvanometer reads zero, the current flowing in the wire AB is :
In the circuit, the galvanometer G shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor R will be :
When two ends of a metallic wire are connected to the terminals of a battery and the heat dissipated in the wire is 10 watt. Now the wire is cut into three identical pieces and these three pieces are joined in parallel combination. If the ends of this combination are connected to the terminals of the same battery, what will be heat dissipated in each wire?
When a current of 2A flows through a metallic wire of radius 1 mm, rate of heat generation is 24 watt. What will be the rate of heat generation when 5 A current flows through a metallic wire made of same material and having same length and radius 2 mm?
A copper rod ABCD is bent in the form of a circular arc as shown in the figure and its two end are connected to the terminals of a battery. If drift velocity of free electrons at the edges AB and CD are V 1 and V 2 respectively, then
Calculate the number of units of electricity used if a bulb of 100 W is kept on for 5 hours.
In the circuit shown in figure resistance of galvanometer coil is 1 Ω . Then
In the arrangement shown, if reading of the ammeter is 1A, find the potential difference between points A and B
In the arrangement shown, find the reading of the ammeter if emf of the battery is 6 volt .
Resistivity of the material of a wire is 6 x 10 -8 ohm-m and the intensity of electric field inside it is 12 x 10 -6 V/m. if cross sectional area of the wire is 1 mm 2 , the electric current flowing through it is
The ends of a resistor are connected to the terminals of a battery of internal resistance 1 Ω . If 75% of the power supplied by the battery is dissipated in the external resistor, find its resistance.
In the arrangement shown initially switch s is open. When switch s is closed,
Two ends of a conductor of variable cross section are connected to the terminals of a battery. E C and E D are intensity of electric field at sections C and D respectively. Then
in the circuit shown, for what value of R, power dissipated in the external circuit is maximum when the value of R is
in the meter bridge shown in figure, initially P/Q = 1. Find the shift in the null point if P is doubled and Q is halved.
in the arrangement shown, readings of ideal voltmeters V 1 , V 2 and V 3 are 20 volt, 50 volt and 60 volt respectively. then current flowing through the current carrying branch is
In the arrangement shown, initially switch S is open and reading of the ammeter is 2.5 A. What will be the reading of the ammeter after the switch S is closed?
Two ends of a copper wire are connected to the terminals of a battery. If the wire is stretched to twice its original length, then power dissipated in the wire. The thermal power dissipated in the wire.
Two metallic wires made of different material, having resistivity ρ and 2 ρ are connected in series combination as shown in the figure. The wires have same cross sectional area. When an electric current passes through the composite wire, intensities of electric fields in wire 1 and 2 are E 1 and E 2 respectively.
Bulb B 1 has rating P 1 watt, V volt and bulb B 2 has rating P 2 watt, V volt. If P 1 > P 2 , then
In the wheat stone bridge shown, no current flows through the galvanometer G. If P and S are interchanged and the galvanometer and the battery are interchanged
In the meter bridge shown in figure, distance of the null point N from end A is 40 cm. When a 20 Ω resistor is connected in series with P, the null point is displaced to the right by 20 cm. Then value of Q is
On increasing the temperature of a conductor, its resistance increases because
The relaxation time in conductors
Drift velocity ν d varies with the intensity of electric field as per the relation
A potential difference of V is applied at the ends of a copper wire of length l and diameter d. On doubling only d, drift velocity
A current I is passing through a wire having two sections P and Q of uniform diameters d and d/2, respectively. If the mean drift velocity of electrons in sections P and Q is denoted by ν P and ν Q respectively, then
The temperature coefficient of resistance for a wire is 0.00125/ 0 C. At 300 K its resistance is 1 ohm. The temperature at which the resistance becomes 2 ohm is
When the length and area of cross-section both are doubled, then its resistance
The specific resistance of a wire is ρ . If its volume is 3 m 3 and its resistance is 3 ohms, then its length will be
In an electrolyte 3.2 × 10 18 bivalent positive ions drift to the right per second while 3.6 × 10 18 monovalent negative ions drift to the left per second. Then the current is
There is a current of 1.344 A in a copper wire whose area of cross-section normal to the length of the wire is 1 mm 2 . If the number of free electrons per cm 3 is 8.4 × 10 22 , then the drift velocity would be
Resistance of tungsten wire at 150 0 C is 133 Ω . Its resistance temperature coefficient is 0.0045 0 C. The resistance of this wire at 500 0 C will be
If the resistance of a conductor is 5 Ω at 50 0 C, and 7 Ω at 100 0 C, then the mean temperature coefficient of resistance of the material is
Two rods of same material and length have their electric resistance in ratio I : 2. When both rods are dipped in water, the correct statement will be
Two wires A and B of same material and same mass have radius 2r and r. If resistance of wire A is 34 Ω then resistance of B will be
A rod of a certain metal is 1.0 m long and 0.6 cm in diameter. Its resistance is 3.0 × 10 − 3 o h m . Another disc made of the same metal is 2.0 cm in diameter and 1.0 mm thick. What is the resistance between the round faces of the disc?
Current flows through a metallic conductor whose area of cross-section increases in the direction of the current. If we move in this direction.
A current I flows through a uniform wire of diameter d when the mean electron drift velocity is v. The same current will flow through a wire of diameter d/2 made of the same material if the mean drift velocity of the electron is
A wire has a non-uniform cross-section as shown in figure. A steady current flows through it. The drift speed of electrons at points P and Q is v P and v Q . Then
An insulating pipe of cross-sectional are a A contains an electrolyte which has two types of ions: their charges being − e and +2e. A potential difference applied between the ends of the pipe result in the drifting of the two types of ions, having drift speed = v (-ve ion) and v/4 (+ve ion). Both ions have the same number per unit volume = n. The current flowing through the pipe is
A current I flows through a cylindrical rod of uniform cross-sectional area A and resistivity ρ . The electric flux through the shaded cross-section of rod as shown in figure is:
Length of a hollow tube is 5 m, its outer diameter is 10 cm and thickness of its wall is 5 mm. If resistivity of the material of the tube is 1 .7 × 10 − 8 Ωm then resistance of tube will be
In an electrical cable there is a single wire of radius 9 mm of copper. Its resistance is The cable is replaced by 6 different insulated copper wires, the radius of each wire is 3 mm. Now the total resistance of the cable will be
A 10V, 1.5Ω cell is connected in series with a variable resistance R whose value can be varied from zero to 1Ω. If ‘R’ is made to gradually increase from zero to 10 Ω, power dissipated in R.
In the network shown in figure power dissipated in the 3Ω resister just after the switch S is closed, is(emf= 10V)
The lowest resistance which can be obtained by connecting 10 resistors each of 1/10 ohm is
You are provided three resistances 2 Ω , 3 Ω and 6 Ω . How will you connect them so as to obtain the equivalent resistance of 4 Ω ?
In the diagram resistance between any two junctions is R. Equivalent resistance across terminals A and B is
In the circuit given E = 6.0 V, R 1 = 100 Ω , R 2 = R 3 = 50 Ω , R 4 = 75 Ω . The equivalent resistance of the circuit, in ohms, is
The equivalent resistance between the points A and B is
In the network shown, when switch S is open balancing length AN 1 = 60 cm and when the switch S is closed, balancing length AN 2 = 50 cm. then the value of r is
A cell of emf 10 V and internal resistance 0.5 Ω is being changed by 2A current as shown in figure. Then chemical energy is stored in the cell at the rate of
Kirchhoff’s second law is based on the law of conservation of
To get the maximum current from a parallel combination of n identical cells each of internal resistance r in an external resistance R, the relation between R and r is
The figure below shows currents in a part of electric circuit. The current i is
When a resistance of 2 ohm is connected across the terminals of a cell, the current is 0.5 A. When the resistance is increased to 5 ohm, the current is 0.25 A. The e.m.f. of the cell is
The magnitude and direction of the current in the circuit shown will be
Two batteries each of emf E and internal resistance r are connected turn by furn in series and in parallel, and are used to find current in an external resistance R. If the current in series is equal to that in parallel, the internal resistance of each battery is:
n identical cells are joined in series with its two cells A and B in the loop with reversed polarities. Emf of each cell is E and internal resistance r. Potential difference across cell A or B is (here n > 4)
In the circuit element given here, if the potential at point B, i.e, V B = 0, then the potentials of A and D ate given as
The current in the adjoining circuit will be
The potential difference between points A and B of adjoining figure is
The reading of the ammeter as per figure shown is
Find current in the branch CD of the circuit.
In the circuit shown below, the current that flows from a to b when the switch S is closed, is
In the circuit shown in figure, potential difference between point A and B is 16 V. Find the current passing through 2 Ω resistance.
In the figure shown, the current flowing through 2 R is
Find the reading of the ideal ammeter connected in the given circuit. Assume that the cells have negligible internal resistance.
In the circuit shown in figure, current through the conductor BC is
The magnitude of i (in ampere) is
In the circuit shown below E 1 = 4 .0 V , R 1 = 2 Ω , E 2 = 6 .0 V , R 2 = 4 Ω and R 3 = 2 Ω . The current i 1 is
Charge flowing through a 10Ω resistor varies with time as shown in the figure. Then power dissipated in the resistor is zero at the instant t =
In the circuit shown in figure, ratio of current flowing through the cell before and after S is closed, is
Which of the following conditions is correct in steady state?
A capacitor is charged using an external battery with a resistance x in series. The dashed line shows the variation of ln I with respect to time t. lf the resistance is changed to 2x, the new graph will be
An ammeter and a voltmeter of resistance R are connected in series to an electric cell of negligible internal resistance. Their readings arc A and V, respectively. If another resistance R is connected in parallel with the voltmeter, then
A voltmeter of resistance 1000 Ω gives full scale deflection when a current of 100 mA flows through it. The shunt resistance required across it to enable it to be used as an ammeter reading 1 A at fulI scale deflection, is
The net resistance of a voltmeter should be large to ensure that
A voltmeter has resistance of 2000 Ω and it can measure upto 2V. If we want to increase its range to 10 V then the required resistance in series will be
An ammeter gives full deflection when a current of 2 A flows through it. The resistance of ammeter is 12 Ω If the same ammeter is to be used for measuring a maximum current of 5 A, then the ammeter must be connected with a resistance of
In the given circuit, the ratio of voltmeter reading to the ammeter reading is R ‘ . If resistance of ammeter is R A and that of voltmeter R V then
We have a galvanometer of resistance 25 Ω It is shunted by a 2 . 5 Ω wire. The part of total current that flows through the galvanometer is given as
A voltmeter having a resistance of 998 Ω is connected to a cell of emf 2 V and internal resistance 2 Ω . The error in the measurement of emf will be
In the circuit shown, the resistance of voltmeter is 10,000 ohm and that of ammeter is 20 ohm. The ammeter reading is 0.10 ampere and voltmeter reading is 12 volt Then R is equal to
In the adjoining circuit, the emf of the cell is 2 volt and the internal resistance is negligible. The resistance of the voltmeter is 80 ohm. The reading of the voltmeter will be
Two resistances of 400 Ω and 800 Ω are connected in series with a 6 volt battery of negligible internal resistance. A voltmeter of resistance 10 , 000 Ω is used to measure the potential difference across 400 Ω . The error in the measurement of potential difference in volts, approximately, is
In the circuit shown in figure, reading of voltmeter is V 1 when only S 1 is closed, is V 2 when only S 2 is closed and is V 3 when both S 1 and S 2 are closed. Then
Resistances R 1 and R 2 , each of 60 Ω , are connected in series as shown in figure. The potential difference between A and B is kept 120 volt. what will be the reading of voltmeter connected between the points C and D if resistance of voltmeter is 120 Ω ?
In the given circuit, the current flowing through the resistance 20 Ω is 0.3 A while the ammeter reads 0.8 A. What is the value of R 1 ?
In the circuit shown here, the readings of the ammeter and voltmeter are (Ammeter and voltmeter are ideal)
A voltmeter with resistance 2500 Ω indicates a voltage of 1 25 V in the circuit shown in figure. What is the series resistance to be connected to voltmeter so that it indicates 100 V? Consider ideal battery.
Voltmeter shown reads 18 v. The resistance of the voltmeter is
Five resistors are connected as shown in the diagram. The equivalent resistance between A and B is
In the circuit shown in the below figure, the potential difference between B and D is zero. The unknown resistance X is of
For what value of unknown resistance X, the potential difference between B and D will be zero in the circuit shown in the figure?
In the given circuit, it is observed that the current I is independent of the value of the resistance R 6 . Then the resistance values must satisfy
A Daniel cell is balanced on 125 cm length of a potentiometer wire. Now the cell is short-circuited by a resistance 2 ohm and the balance is obtained at 100 cm. The internal resistance of the Daniel cell is
A potentiometer is an ideal device of measuring potential difference because
For comparing the e.m.f.’s of two cells with a potentiometer, a standard cell is used to develop a potential gradient along the wires. Which of the following possibilities would make the experiment unsuccessful?
A battery of 6 volts is connected to the terminals of a three metre long wire of uniform thickness and resistance of the order of 100 Ω The difference of potential between two points separated by 50 cm on the wire will be
If the length of potentiometer wire is increased, then the length of the previously obtained balance point will
A 2 volt battery, a 15 Ω resistor and a potentiometer of 100 cm length, all are connected in series. If the resistance of potentiometer wire is 5 Ω then the potential gradient of the potentiometer wire is
In the Wheatstone’s bridge (shown in figure), X = Y and A > B. The direction of the current between ab will be
The figure shows a circuit diagram of a Wheatstone bridge to measure the resistance G of the galvanometer. The relation P Q = R G will be satisfied only when
In the following Wheatstone bridge, P/Q = R/S. If key K is closed, then the galvanometer will show deflection
In an experiment to measure the internal resistance of a cell by potentiometer, it is found that the balance point is at a length of 2m when the cell is shunted by a 5 Ω resistance, and is at a length of 3m when the cell is shunted by a 10 Ω resistance. The internal resistance of the cell is
A resistance of 4 Ω and a wire of length 5 metres and resistance 5 Ω are joined in series and connected to a cell of e.m.f. 10 V and internal resistance 1 Ω . A parallel combination of two identical cells is balanced across 300 cm of the wire. The e.m.f. E of each cell is
AB is a potentiometer wire of length 100 cm and its resistance is 10 ohms. It is connected in series with a resistance R = 40 ohms and a battery of e.m.f. 2 V and negligible internal resistance. If a source of unknown e.m.f. E is balanced by 40 cm length of the potentiometer wire, the value of E is
The figure shows a meter-bridge circuit where X = 12 Ω and R = 18 Ω . The jockey J is at the null point. If R is made 8 Ω through what distance will the jockey J have to be moved to obtain null point again?
For the arrangement of the potentiometer shown in the figure, the balance point is obtained at a distance 75 cm from A when the key fr is open. The second balance point is obtained at 60 cm from A when the key k is closed. Find the internal resistance of the battery E 1 .
AB and CD are two uniform resistance wires of lengths 100 cm and 80 cm, respectively. The connections are shown in the figure. The cell of emf 5 V is ideal while the other cell of emf E has internal resistance 2 Ω A length of 20 cm of wire CD is balanced by 40 cm of wire AB. Find the emf E in volt, if the reading of the ideal ammeter is 2 A. The other connecting wires have negligible resistance.
One of the circuits for the measurement of resistance by potentiometer is shown. The galvanometer is connected at point A and zero deflection is observed at length PJ = 30 cm. In second case the secondary cell is changed. Take E S = 10 V and r = 1 Ω in 1st reading and E S = 5 V and r = 2 Ω in 2nd reading. In second case, the zero deflection is observed at length PJ = 10 cm. What is the resistance R (in ohm)?
In the given potentiometer circuit, length of the wire AB is 3 m and resistance is R = 4.5 Ω . The length AC for no deflection in galvanometer is
A battery of emf ε 0 = 12 V is connected across a 4 m long uniform wire having resistance 4 Ω / m . The cells of small emfs ε 1 = 2 V and ε 2 = 2 V having internal resistance 2 Ω and 6 Ω , respectively, are connected as shown in the figure. If galvanometer shows no deflection at the point N, the distance of point N from the point A is equal to
Resistance of 100 cm long potentiometer wire is 10 Ω . It is connected to a battery (2 volt) and a resistance R in series. A source of 10 mV gives null point at 40 cm length, then external resistance R is
In a metre bridge experiment, null point is obtained at 20 cm from one end of the wire when resistance X is balanced against another resistance Y. If X < Y, then where will be the new position of the null point from the same end, if one decides to balance a resistance of 4X against Y?
In the potentiometer arrangement shown in figure, null point is obtained at length l . Column I Column II i. If E 1 is increased p. l should increase ii. If R is increased q. I should decreases iii. If E 2 is increased r. l should remain the same to again get the null point Now, match the given columns and select the correct option from the codes given below.
For the circuit shown, a shorting wire of negligible resistance is added to the circuit between points, A and B. when this shorting wire is added, bulb 3 goes out. which bulb(s) in the circuit brighten? All bulbs are identical.
Two bulbs rated 25 W − 220 V and 100 W − 220 V are connected in series to a 440 V line. which one is likely to fuse?
According to Joule’s law, if the potential difference across a conductor having a material of specific resistance remains constant,then the heat produced in the conductor is directly proportional to
Two wires A and,B of the same material have their lengths in the ratio 1 : 2 and radii in the ratio 2 : 1. The two wires are connected in parallel across a battery. The ratio of the heat produced in A to the heat produced in B for the same time is
Consider four circuits shown in the figure below. In which circuit power dissipated is greatest? (Neglect the internal resistance of the Power supply)
Two bulbs of 500 watt and 200 watt are manufactured to operate on 220 volt line. The ratio of heat produced in 500 W and 200 W, in two cases, when firstly they are joined in parallel and secondly in series, will be
Two resistors having equal resistances are joined in series and a current is passed through the combination. Neglect any variation in resistance as the temperature changes. In a given time interval
If two bulbs of watt age 25 and 100, respectively, each rated at 220 volt are connected in series with the supply of 440 volt, then which bulbs will fuse?
A 100 watt bulb working on 200 volt and a200 watt bulb working on 100 volt have
Two resistances R 1 and R 2 when connected in series and parallel with 120 V line, power consumed will be 25 W and 100 W, respectively. Then the ratio of power consumed by R 1 to that consumed by R 2 will be
Two heaters A and B are in parallel across the supply voltage. Heater A produces 500 kJ in 20 minutes and B produces 1000 kJ in 10 minutes. The resistance of A is 100 Ω . If the same heaters are connected in series across the same voltage, then total heat produced in 5 minutes will be
What will happen when a 40 watt-220 volt lamp and a 100 watt-220 volt lamp are connected in series across 40 volt supply?
The current in C is 2 A. The rate of heat loss in A, B and c are 1.20, 0.60 and 1.20 J/s, respectively. The emf of the cell [for cell internal resistance – 0] is
Two bulbs X and Y having same voltage rating and of power 40 watt and 60 watt, respectively, are connected in series across a potential difference of 300 volt, then
In an electric circuit shown in the figure, the external resistance R is variable. It is found that same power is developed in external resistance R if its value is either 5 Ω or 20 Ω . With this information find the internal resistance (r) of the voltage source.
The resistance of the filament of an electric bulb changes with temperature. If an electric bulb rated 220 volt and 100 watt is connected to a (220 x .8) volt source, then the actual power would be
The resistance of a heater coil is 110 ohm. A resistance R is connected in parallel with it and the combination is joined in series with a resistance of 11 ohm to a 220 volt main line. The heater operates with a power of I10 watt. The value of R in ohm is
An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from room temperature 20 0 C? The temperature of boiling water is
An electric bulb rated for 500 watts at 100 volts is used in a circuit having a 200 volt supply. The resistance R that must be put in series with the bulb so that the bulb draws 500 W is
A 100 W bulb B 1 and two 60 W bulbs B 2 and B 3 are connected to a 250 V source, as shown in the figure. Now W 1 , W 2 and W 3 are the output powers of the bulbs B 1 , B 2 and B 3 , respectively. Then
Four identical electrical lamps are labelled 1.5 V 0.5 A which describes the condition necessary for them to operate at normal brightness. If a 12 V battery of negligible internal resistance is connected to lamps as shown, then
The wiring of a house has resistance 6 Ω . A 100 W bulb is glowing. If a geyser of 1000 W is switched on, the change in potential drop across the bulb is nearly (Supply voltage is 220 V)
If a 30 V 90 w bulb is to be worked on a 120 V line, a resistance of how many ohms should be connected in series with the bulb?
Battery shown in figure has e.m.f. E and internal resistance r. Current in the circuit can be varied by sliding the contact J.If at any instant current flowing through the circuit is I, potential difference between terminals of the cell is V, thermal power generated in the cell is equal to η fraction of total electrical power generated in it, then which of the following graphs is correct?
In order to determine the e.m.f. of a storage battery it was connected in series with a standard cell (both are adding) in a certain circuit and a current I 1 was obtained. When polarity of the standard cell is reversed, a current I 2 . was obtained in the same direction as that of I 1 . What is the e.m.f. ε 1 of the storage battery? The e.m.f. of the standard cell is ε 2
In the circuit shown, the reading of ammeter is
In the circuit shown a current through 20 Ω resistor equals
A time varying current i is passed through a resistance R as shown in figure. The total heat generated in the resistance is
A constant voltage is applied between the two ends of a uniform metallic wire. Some heat is developed in it. The heat developed is doubled if
Two conductors AB and CD are connected between two parallel resistors in such a way that no current flows through them. Then a wire is connected between E and F. Now choose the correct statement.
For ensuring dissipation of same energy in all three resistors (R 1 , R 2 and R 3 ) connected as shown in figure, their values must be related as:
In the arrangement shown in figure, when the switch S 2 is open, the galvanometer shows no deflection for l = L 2 . When the switch S 2 is closed, the galvanometer shows no deflection for l = 5 L 12 . The internal resistance (r) of 6 V cell, and the emf E of the other battery are respectively
A steady current flows in a metallic conductor of nonuniform cross-section. The quantity/ quantities constant along the length of the conductor is/are
Masses of 3 wires of same metal are in the ratio 1 : 2 : 3 and their lengths are in the ratio 3 : 2 : 1. The electrical resistances are in the ratio
In a Wheatstone’s bridge, all the four arms have equal resistance R. If the resistance of the galvanometer arm is also R, the equivalent resistance of the combination as seen by the battery is
The material of fuse wire should have
What is immaterial for an electric fuse wire?
The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then
A 6 V battery is connected to the terminals of a three metre long wire of uniform thickness and resistance of 100 Ω . The difference of potential between two points on the wire separated by a distance or 50 cm, will be
Find the equivalent resistance between the points a and b.
In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, the resistance of a 60 W bulb for use in USA will be
For the network shown in the figure, the value of the current i is
A 5-A fuse wire can withstand a maximum power of 1 W in circuit. The resistance of the fuse wire is
A heater coil is cut into two parts of equal length and one of them is used in the heater. The ratio of the heat produced by this half coil to that by the original coil is
Kirchhoff’s first and second laws for electrical circuits are consequences of
In the circuit shown, if a conducting wire is connected between point s A and^B, the current in this wire willsss
Two cells, having the same emf, are connected in series through an external resistance R. Cells have internal resistances r 1 and r 2 (r 1 > r 2 ), respectively. Which the circuit is closed, the potential difference across the first cell is zero. The value of R is
Power dissipated across the 8 Ω resistor in the circuit shown here is 2 W. The power dissipated in watt units across the 3 Ω resistor is
A current of 3 A flows through the 2 Ω resistor as shown in the circuit. The power dissipated in the 5 Ω resistor is
A cell can be balanced against 110 cm and 100 cm of potentiometer wire, respectively, with and without being short circuited through a resistance of 10 Ω Its internal resistance is
A galvanometer of resistance 50 Ω is connected to a battery of 3 V along with a resistance of 2950 Ω in series. A full-scale deflection of 30 divisions is obtained in the galvanometer. In order to reduce this deflection to 20 divisions, the resistance in series should be
A wire of resistance 12 Ω m − 1 is bent to form a complete circle of radius 10 cm. The resistance between its two diametrically opposite point s, A and B, as shown in the figure, is
A student measures the terminal potential difference (V) of a cell (of emf ε and internal resistance r) as a function of the current (I) flowing through it. The slope and intercept of the graph between V and I, then, respectively, equal
Statement 1: Consider the two situations shown in the figure. Potential difference between points A and B in case I is more as compared to case II. Statement 2: In case I : V A − V B = E + Ir In case II: V A − V B = E − Ir
Statement 1: When the length of a conductor is stretched to double, its resistance will also get doubled. Statement 2: Resistance is inversely proportional to the length of a conductor.
Statement 1: Potential measured by a voltmeter across a wire is always less than the actual potential difference across it. Statement 2: Finite resistance of voltmeter changes current flowing through the resistance across which potential difference is to be measured.
Statement 1: Insulators do not allow flow of current through them. Statement 2: Insulators have no free charge carriers.
Statement 1: There is no current in the metals in the absence of electric field. Statement 2: Motion of free electrons is random.
Statement 1: A person touching a high power line gets stuck with the line. Statement 2: The current carrying wires attract the man towards it.
Statement 1: The connecting wires are made of copper. Statement 2: The electrical conductivity of copper is high.
Statement 1: The 200 w bulbs glows with more brightness then 100 W bulbs. Statement 2: A 100 W bulb has more resistance than a 200 W bulb.
Statement 1: Fuse wire must have high resistance and low melting point. Statement 2: Fuse is used for a maximum limiting current flow only.
Statement 1: Two electric bulbs of 50 W and 100 W are given. When connected in series, 50 w bulb glows more but when connected in parallel, 100 W bulb glows more. Statement 2: In series combination, power is directly proportional to the resistance of circuit. But in parallel combination, power is inversely proportional to the resistance of the circuit.
Statement 1: Two bulbs of same wattage, one having a carbon filament and the other having a metallic filament are connected in series. Metallic bulb will glow more brightly than carbon filament bulb. Statement 2: Carbon is a semiconductor.
Statement 1: Though the same current flows through the line wires and the filament of the bulb but heat produced in the filament is much higher than that in line wires. Statement 2: The filament of bulbs is made of a material of high resistance and high melting point.
Statement 1: If three identical bulbs are connected in series as shown in figure, then on closing the switche bulb C is short circuited and hence illumination of bulbs A and B decreases. Statement 2: Voltage on A and ,B decreases.
The resistance of the series combination of two resistance is S. When they are joined in parallel the total resistance is P. If S = nP, then the minimum possible value of n is
An energy source will supply a constant current into the load if its internal resistance is
In a potentiometer experiment, the balancing with a cell is at length 240 cm. On shunting the cell with a resistance of 2 Ω the balancing length becomes 120 cm. The internal resistance of the cell is
The current from the battery in circuit diagram shown is
In the circuit shown in the figure, the current through
A wire of length L and 3 identical cells of negligible internal resistances are connected in series. Due to current, the temperature of the wire is raised by Δ T in time t. A number N of similar cells is now connected in series with a wire of the same material and cross-section but of length 2L.The temperature of the wire is raised by the same amount Δ T in the same time t. The value of N is
Six equal resistances are connected between points P, Q and R as shown in the figure. Then the net resistance will be maximum between
A wire when connected to 220 V mains supply has power dissipation P 1 . Now the wire is cut into two equal pieces which are connected in parallel to the same supply. power dissipation in this case is P 2 . Then P 2 : P 1 is
A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be
The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use?
The cell has an emf of 2 V and the internal resistance of this cell is 0.1 Ω . It is connected to resistance of 3.9 Ω , the voltage across the cell will be
An electric bulb, marked 40 W and 200 V is used in a circuit of supply voltage 100 V. Now its power is
The voltage of clouds is 4 × 10 6 V with respect to ground. In a lightning strike lasting 100 ms, a charge of 4 C is delivered to the ground. The power of lightning strike is
If resistance of the filament increases with temperature, what will be power dissipated in a 220 V − 100 W lamp when connected to 110 V power supply?
What is the drift velocity of electrons in Silver wire of 2 mm radius, carrying a current of 4 A and having number of electrons per unit volume as 5 . 8 × 10 28 m – 3 .
If a wire of 1 ohm resistance is stretched to double its length, then the resistance will become
Consider all possible values of R in circuit shown. Then the maximum possible rate at which energy can be supplied by the ideal battery to the given combination of resistors is equal to
In the figure shown the power generated in y is maximum when y = 5 Ω Then R is :
Consider a wire having current 10A having area of cross-section 1 cm 2 . If number of electrons per unit volume is 9 × 10 28 m − 3 . Find the drift velocity of electrons:
Four circuits are given in the options below. In all the circuits voltmeters, ammeter and cells are ideal. The readings of each ammeter and voltmeter are shown in their neighborhood (in bold letters). In which pair of circuits shown below, readings of voltmeters V 1 and V 2 and ammeter A may be correct ?
Drift velocity v d varies with the intensity of electric field as the relation :
In the circuit shown below E 1 = 4.0 V, R 1 = 2 Ω E 2 = 6.0 V, R 2 = 4 Ω and R 3 = 2 Ω . The current I 1 is:
The temperature coefficient of resistance of wire is 12.5 × 10 -4 /C° . At 300 K the resistance of the wire is 1 ohm. The temperature at which resistance will be 2 ohm is
If voltage across a bulb rated 220 V and 100 W drops by 2.5% of its rated value, by which the power would decrease is,
The efficiency of a cell when connected to a resistance R is 60%. What will be its efficiency if the external resistance is increased to six times.
The resistance of a resistance thermometer has values 2.70 Ω and 3.70 Ω at 0°C and 100°C respectively. The temperature at which the resistance is 3.10 Ω is
An ammeter and a voltmeter are connected in series to a battery of emf 6.0 volt. When a certain resistance is connected in parallel with the voltmeter, the reading of the voltmeter decreases two times whereas the reading of the ammeter increases the same number of times. Find the voltmeter reading after the connection of the resistance :
5 ampere of current is passed through a metallic conductor. The charge flowing in one minute in coulomb will be:
In an electrical cable there is a single wire of radius 9 mm of copper. Its resistance is 5Ω . The cable is replaced by 6 different insulated copper wires, the radius of each wire is 3 mm . Now the total resistance of the cable will be
Two uniform wires A and B are of the same metal and have equal masses. The radius of wire A is twice that of wire B . The total resistance of A and B when connected in parallel is
Twelve wires of equal length and same cross-section are connected in the form of a cube. If the resistance of each of the wires is R , then the effective resistance between the two diagonal ends would be
You are given several identical resistances each of value R = 10Ω and each capable of carrying maximum current of 1 ampere. It is required to make a suitable combination of these resistances to produce a resistance of 5Ω which can carry a current of 4 amperes. The minimum number of resistances of the type R that will be required for this job
In a meter bridge circuit as shown, when one more resistance of 100 Ω is connected is parallel with unknown resistance x, then ratio l 1 l 2 become 2. If l 1 is balance length of the uniform wire A B, then the value of x must be:
Assume that each atom of copper contributes one free electron, If the current flowing through a copper wire of 1 mm diameter is 1.1 A, the drift velocity of electrons will be [density of Cu = 9gcm -3 , At. wt. of Cu = 63)
There is a current of 1.344 amp in a copper wire whose area of cross-section normal to the length of the wire is 1mm 2 . If the number of free electrons per cm 3 is 8.4x 10 22 then the drift velocity would be
A current of 4.8 amp. is flowing in a conductor. The number of electrons flowing per second through the conductor will be
An electron of hydrogen atom is considered to be revolving round the proton in circular orbit of radius h 2 4 π 2 me 2 with velocity 2 πe 2 h The equivalent current due to circulating charge is
Two resistances are joined in parallel whose resultant 6/5 ohm. One of the resistance wire is broken and the effective resistance becomes 2 ohm. Then the Resistance in ohm of the wire that got broken was
Three 2 ohm resistors are connected to form a triangle. The resistance between any two corner is
You are given several identical resistances each of value -R=10 Ω and each capable of carrying a maximum current of one ampere. It is required to make a suitable combination of these resistances of 5 Ω which can carry a current of 4 ampere. The minimum number of resistances of the type R that will be required for this job is
A battery of 6 volt is connected to the terminals of a three-metre long wire of uniform thickness and resistance of the order of 100 ohm. The difference of potential between two points separated by 50 cm on the wire will be
Two wires of same metal have same length, but their cross sections are in the ratio 3 : 1. They are joined in series. The resistance of thicker wire is 10 Ω .The total resistance of the combination will be
An electrical cable of copper has just one wire of radius 9 mm. Its resistance is 5 ohm. This single copper wire of the cable is replaced by 6 different well insulated copper wires each of radius 3 mm. The total resistance of the cable will now be equal to
A cylindrical copper rod is reformed to twice its original length with no change in volume. The resistance between its ends before the change was R Now its resistance will be
A material B has twice the specific resistance of A. A circular wire made of B has twice the diameter of a wire made of A. Then for the two wires to have the same resistance, the ratio of l B / l A of their respective lengths must be
If a wire is stretched such that its area of cross-section becomes (1 / n) times, then its resistance will became
A 50 volt battery is connected across 10 ohm resistor. The current is 4. 5 ampere. The internal resistance of the battery is
Each of the resistances in the network shown in fig in equal to ,R. The resistance between the terminals A and B is
The Kirchhoff’s ( Σi = 0 ) first law and second law ( ΣiR = ΣE ) where the symbols have their usual meanings, are respectively based on
A current of 2 amp. flows in a system of conductors show in fig. The potential difference V A – V B will be
Four resistors are connected as shown in fig.6V battery of negligible resistance is connected across terminal AC. The potential difference across terminals B, D will be
The current in the circuit of fig.is
Four wires AB, BC, CD and DA of resistance 4 Ω each and fifth wire BD of resistance 8 Ω are joined to form a rectangle AB CD of which BD is diagonal. The effective resistance between the points A and B [Fig] is
The equivalent resistance between the points X and Y of the following fig is
Fig. shows current in a part of electrical circuit then current i is
In the circuit of fig. the final voltage drop across the capacitor C is
Two cells of the same e.m.f. e but different internal resistances,R 1 and R 2 , are connected in series with an external resistance R. The potential drop across the first cell is found to be zero. The external resistance R [Fig.] is
A torch bulb rated as 4.5 W, 1.5 V is connected as shown in fig. The e.m.f. of the cell, needed to make the bulb glow at full intensity is
There are N cells in the circuit of fig. The e.m.f’ and internal resistance of each cell is E and r respectively. The points A and I in the circuit divide the circuit into n and (N -n) cells. The current in the circuit is
Find the resistance of the portion of the circuit between A and B in the circuit shown in fig Points A and P are connected by a copper wire of negligible resistance. Similarly, Points B and Q are also connected by a copper wire of negligible resistance
In a Wheatstone’s bridge, three resistances P, Q and R are connected in the three arms and fourth arm is formed by two resistances S 1 , and S 2 , connected in parallel. The condition for the bridge to be balanced will be
Fig. shows a potentiometer circuit to determine the unknown e.m.f. E. When the jockey makes contact at point A, the deflection is towards left. On moving the jockey from A to B, the deflection always remains towards left but goes on decreasing. This means that
Resistances of 6 Ω each are connected in the manner shown in fig. With the current 0.5 ampere as shown in the figure, the potential difference Vp -V Q is
In the circuit shown in fig. the potential difference between points A and B will be
An ideal gas is contained in a thermally insulated and rigid container. The gas is heated through a resistance of 100 Ω by passing a current of 1 amp. The change in the internal energy of the gas after S min. will be
The mass and charge of an electron are m and e respectively. The momentum acquired by the electrons in l cm of wire when a current i starts to flow is
If E denotes electric field in a uniform conductor, i corresponding current through it and v7 drift velocity of electrons, then which of the following graphs is correct
A uniform wire of resistance 36 ohm is bent in the form of a circle as shown in fig The effective resistance across the points A and B is
In the given network, Fig. the equivalent resistance between A and B is
An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of (4/3) and (2/3), then the ratio of the currents passing through the wires will be
A potential difference is applied across the ends of a metallic wire. If the potential difference doubled, the drift velocity
If a copper wire is stretched to make it 0.1% longer, the percentage increase in resistance will be
Two identical cells connected in series send 10 amp current through a 5 Ω resistor. When they ale connected in parallel, they send 8 amp current through the same resistance. What is the internal resistance of each cell
A current i flows in a wire of circular cross-section with the free electrons travelling with a drift velocity v. The drift velocity of electron when a current 2 i flows in another wire of twice the radius and of the same material is
The lamp of flash light is 1 .5 Ω . It uses 3 cells each of 1 . 5 V and internal resistance 0 . 25 Ω . What is the net potential difference across the lamp ?
Four wires of equal length and of resistance 10 Ω each are connected in the form of a square. The equivalent resistance between two opposite corners of the square is
A certain piece of copper is to be shaped into a conductor of minimum resistance. Its length and diameter should be respectively
A uniform wire of resistance 20 ohm having resistance 1 Ω /m is bent in form of a circle as shown in fig. If the equivalent resistance between M and N is 1.8 Ω , then the length of the shorter section is
The resistance across M and N in the given fig. is
If a rod has resistance 4 Ω and if rod is turned as half cycle then the resistance along diameter
Two resistances are connected in two gaps of a metre bridge. The balance point is 20 cm from the zero end. A resistance of 15 ohm is connected in series with the smaller of the two. The null point shifts to 40 cm. The value of the smaller resistance in ohm is
In the given circuit, the voltmeter records 5 volt. The resistance of the voltmeter in ohms is
In the given circuit, what will be the equivalent resistance between the points A and B ?
When a wire of uniform cross-section a length / and resistance R is bent into a complete circle, the resistance between any two of diametrically opposite points will be
Two batteries, one of e.m.f. 18 volt and internal resistance 2 Ω and the other of e.m.f. 12 volt and internal resistance 1C) are connected as shown in fig, The voltmeter V will record a reading of
An energy source will supply a constant current i[to the load if its internal resistance is
‘Two sources of equal e.m.f, are connected to an external resistance .R. The internal resistances of the two sources are R 1 , and R 2 (R 2 >R 1 ) If the potential difference across the source having internal resistance .R 2 , is zero, then
In a metre bridge [Fig], the gaps are closed by two resistances P and Q and the balance point is obtained at 40 cm. When Q is shunted by resistance of 10 Ω , the balance point shifts to 50 cm. The values of P and Q are
A thin uniform wire AB of length 1 m, and unknown resistance X and a resistance of 12 Ω are connected by thick conducting strips as shown in fig. A battery and galvanometer are also connected as shown in the figure. It is found that no deflection takes place in the galvanometer when the sliding jockey touches the wire at a distance of 60 cm from A. The unknown resistance X is
A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/quantities constant along the length of the conductor is/are
The effective resistance between points P and Q of the electric circuit shown in fig. is
Which of the following circuits is correct for the verification of Ohm’s law ?
A constant voltage is applied between the two ends of a uniform metallic wire. Some heat is developed in it. The heat developed is doubled if
A resistor R 1 dissipates the power P when connected to a certain generator. If a resistor,R 2 is put in series with R 1 , the power dissipated by R 1 ,
You are given resistance wire of length 50cms and a battery of negligible resistance. In which of the. following cases is largest amount of heat generated
Two heater wires of equal length are first connected in series and then in parallel. The ratio of heat produced in the two cases is
If two bulbs of wattage 25 and 100 respectively each rated at 220 volt are connected in series with the supply of 440 volt, which bulb will fuse ?
Two electric bulbs have tungsten filament of same length. If one of them gives 60 watts and other 100 watts, then
Three equal resistors connected in series across a source of e.m.f. together dissipate 10 watts of power. What would be power dissipated if the same resistors are connected in parallel across the same source of e.m.f.
A 25 watt ,220 V and a 100 watt ,220V bulbs are joined in series and connected to the mains. Which bulb will glow brighter
Two 1000 W heaters when connected in parallel across 220 V supply produce heat H p in time t. If they are connected in series across the same power supply, the heat produced in the same time is H S . What is (H P / HS) ?
A fuse wire with a circular cross-sectional radius of o.02 mm blows with a current of 5 ampere. For what current another fuse wire made from the same material with cross-sectional radius of 0.04 mm will blow ?
The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not is use ?
A heater coil is cut in two equal parts and only one part is now used in the heater. The heat generated will now be
Two electric lamps of 40 watt each are connected in parallel. The power consumed by the combination will be
A heater boils 1 kg of water in time t 1 , and another heater boils the same water in time t 2 . If both are connected in series, the combination will boil the same water in time
In a circuit shown in fig. the heat produced in 5 ohm resistor due to a current flowing in it is 10 calories per second. The heat produced in 4 ohm resistor is
An electric cable having a resistance of 0.4 Ω delivers 10 kW at 200 v dc to a factory. The efficiency of transmission is
Resistance of conductor is doubled keeping potential difference across it constant. The rate of generation of heat will
A 5 amp fuse wire can withstand a maximum power of 1 watt in the circuit, The resistance of the fuse wire is
Let H 1 be the heat generated per second in the filament of 100 W, 250 V lamp and H, be that in filament of 200 W, 250 V lamp. Which of the following is correct ?
50 electric bulbs are connected in series across a 220 V supply and the illumination produces is i 1 ,. 5 bulbs are fused. If the remaining 45 are again connected in series, the illumination produces is i 2 . Which of the following is true ?
What is immaterial for an electric fuse wire ?
Two bulbs which consume powers P 1 , and P 2 , are connected in series. The power consumed by the combination is
Two heater wires of equal length are first connected in series and then in parallel. The ratio of heat produced in the two cases is
Two electric bulbs have tungsten filament of same length. If one of them gives 60 watt and other 100 watt, then
A 25 wad and a 100 watt bulbs are joined in series and connected to the mains. Which bulb will glow brighter ?
The capacitor C is initially without charge. X is now joined to y fig. for a long time, during which H 1 , heat is produced in the resistance R. X is now joined to Z for a long time, during which H 2 , heat is produced in R
A wire of length L and 3 identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised by ∆ T in a time t. A number N of similar cells is now connected in series with a wire of same material and cross-section but of length 2 I- The temperature of the wire is raised by the same amount ∆ T in the same time t. The value of N is
