Galvanometer with 50 divisions on the scale has a resistance of 25 Ω . A current of 2 × 10 -4 A gives a deflection of one scale division. The additional series resistance required to convert it into a voltmeter reading up to 25 V is ……….. ohm.
Figure shows a simple potentiometer circuit for measuring a small e.m.f. produced by a thermocouple. The meter wire PQ has a resistance 5 Ω and the driver cell has an e.m.f. of 2 V. If a balance point is obtained 0.600 m along PQ when measuring an e.m.f. of 6.00 mV, what is the value of resistance R
Find the equivalent resistance between A and B
The actual value of resistance ‘R’ shown in the figure is 50 Ω . This is measured in an experiment as shown using the standard formula R = V I where V and I are the readings of Voltmeter and Ammeter respectively . If the measured value of R is 5% less, then the internal resistance of the voltmeter is,
Four resistances of 15 Ω , 12 Ω , 4 Ω and 10 Ω respectively in cyclic order to form Wheatstone’s network. The resistance that is to be connected in parallel with the resistance of 10 Ω to balance the network is Ω .
The current in resistance R 1 in the given circuit is
In a meter bridge experiment, initially the jockey is at null point. Now resistance R 1 and R 2 is interchanged. Shift in the position of jockey is cm
The length of potentiometer wire is 1200cm and it carries a current 30 mA. For a cell of emf 5V and internal resistance of 20 Ω . The null point on it is found to be at 1000 cm. The resistance of whole wire is
Consider a wire of length 0.1 m with an area of cross section 1 mm 2 connected to 5 V. Find the current flowing through the metallic wire where μ = 5 × 10 − 6 m 2 v − 1 s − 1 , e = 1.6 × 10 − 19 C and n = 8 × 10 28 m − 3
Two wires of resistances R 1 and R 2 have temperature coefficient of resistances α 1 and α 2 respectively . These are joined in series. The effective temperature coefficient of resistance is
A, B and C are voltmeters of resistance R , 1.5 R and 3R respectively. When some potential difference applied between X and Y . The voltmeter readings are V A , V B and V C respectively
In a wheat stones bridge , three resistance P, Q and R are connected in three arms and the 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
The actual value of resistance ‘R’ , shown in the figure is 40 Ω . This is measured in an experiment as shown using the standard formula R = V I , where V and I are the readings of the voltmeter and ammeter respectively. If the measured value of R is 5 % less, then the internal resistance of the voltmeter is
The wheat stone bridge shown in fig here gets balanced when the carbon resistor used as R 1 has the colour code (Red,Yellow , Brown). The resistors R 2 and R 4 are 80 Ω and 40 Ω respectively. Assuming the colour code for the carbon resistors gives their accurate values the colour code for the carbon resistor used as R 3 would be
In the figure shown, what is the current (in Ampere) drawn from the battery ? you are given R 1 = 15 Ω , R 2 = 10 Ω , R 3 = 20 Ω , R 4 = 5 Ω , R 5 = 25 Ω , R 6 = 30 Ω , E = 25 V
A ring is made of a wire having a resistance R 0 =12 Ω . Find the points A and B as shown in fig. at which a current carrying conductor should be connected so that the resistance ‘R’ of the sub circuit between these points is equal to 8 3 Ω
A material of resistivity ρ is formed in the shape of truncated cone of altitude ‘h’ as shown in the fig. the top end has radius ‘a’ while bottom ‘b’. Assuming a uniform current density through any circular cross section of the cone. The resistance between two ends is :
Suppose the colours on the resistor as shown fig. are brown, yellow , green and gold. Find the resistance of the resistor
A straight conductor of uniform cross-section carries a current ‘ i ’. Let S = specific charge of an electron. The momentum of all the free electrons per unit length of the conductor due to their drift velocity only is
Two fuse wires are made of the same material the radius of first and second wires are r 1 = 2 mm and r 2 = 4 mm . The first wire blows when a current of 15 A passes through it. Find the current require to blow the second wire
The expression for thermo emf in a thermo couple is given by the relation E = 40 θ − θ 2 20 , where θ is the temperature difference of two junctions. For this , the neutral temperature will be …….. o C
The length of a potentiometer wire is 1200cm and it carries a current of 60mA. For a cell of emf 5V and internal resistance of 20 Ω , the null point on it is found to be at 1000cm. the resistance of whole wire is:
The series combination of two batteries, both of the same emf 10 V, but different internal resistance of 20 Ω and 5 Ω , is connected to the parallel combination of two resistors 30 Ω and x Ω . The voltage difference across the battery of internal resistance 20 Ω is zero, the value of x(in Ω ) is ——
In the given circuit diagram, a wire is joining points B and D. The current in this wire is :
In a meter bridge experiment S is a standard resistance. R is a resistance wire. It is found that balancing length is l = 25 c m . If R is replaced by a wire of half length and half diameter that of R of same material, then the balancing distance l ‘ (in cm) will now be
Consider four conducting materials copper, tungsten, mercury and aluminium with resistivity ρ C , ρ T , ρ M and ρ A respectively. Then
A potentiometer wire PQ of 1 m length is connected to a standard cell E 1 . Another cell E 2 of emf 1.02 V is connected with a resistance ‘r’ and switch S (as shown in figure). With switch S open, the null position is obtained at a distance of 49 cm from Q. The potential gradient in the potentiometer wire is:
The value of current i 1 flowing from A to C in the circuit diagram is:
A galvanometer of resistance G is converted into a voltmeter of range 0 − 1 V by connecting a resistance R 1 in series with it. The additional resistance that should be connected in series with R 1 to increase the range of the voltmeter to 0 − 2 V will be:
In the part of a circuit shown in fig, the potential difference V H − V G between points G and H will be
What is the reading of voltmeter (in volts) in the following figure?
If the length of the filament of a heater is reduced by 10% by cutting its length, the power of the heater will be nearly, (if constant voltage is maintained across the heater)
Two meters of voltage range 20.0V and 30.0V have to be constructed with a galvanometer. The resistance connected in series with the galvanometer is 1680 Ω for the 20.0V range and 2930 Ω for the 30.0V range. The resistance of the galvanometer and the full -scale current are respectively.
The resistance wire AB in the balancing setup shown in figure is 10 cm long. When AC = 40 cm, no deflection occurs in the galvanometer. The unknown resistance R (in Ω ) is
The current I 1 (in A) flowing through 1 Ω resistor in the following circuit is
A galvanometer having coil resistance 100 Ω gives a full scale deflection when a current of 10 mA is passed through it. What is the value of the resistance which can convert this galvanometer into a voltmeter giving full scale deflection for a potential difference of 10 V ?
In the given circuit diagram a wire is joining points B and D. The current in this wire is
Find the equivalent resistance between A and B
Two electric bulbs rated 25 W, 220 V and 100 W,220 V and connected in series across a 220 V voltage source. The 25 W and 100 W bulbs now draw P 1 and P 2 powers respectively (i) P 1 = 16 W (ii) P 1 = 4 W (iii) P 2 = 16 W (iv) P 2 = 4 W
In the circuit shown in the figure , if the potential at point A is taken to be zero. The potential at point B is
The value of current ‘ i ‘ is :
A resistance is shown in the figure. Its value and tolerance are given respectively by :
In the circuit the potential difference between A and B is
In a meter bridge , the wire of length 1 m has a non-uniform cross-section such that, the variation d R d l of its resistance R with length l is d R d l α 1 l , two equal resistances are connected as shown in the figure. The galvanometer has zero deflection when the jockey is at point P. What is the length AP ?
A wire of resistance ‘R’ is elongated n-fold to make a new uniform wire. The resistance of new wire
The V-I graph for a conductor temperatures T 1 and T 2 are as shown in the fig. T 2 − T 1 is proportional to
The n rows each containing m cells in series are joined in parallel. Maximum current is taken from this combination across an external resistance of 3 Ω . If the total number of cells used are 24 internal resistance of each cell is 0.5 Ω .Then
In the circuit given here the points A, B and C are 70 V , zero and 10 V respectively. Then
In the given circuit [choose the incorrect option]
Three resistance P,Q, R each of 2 Ω and an unknown resistance ‘S’ from the four arms of a wheat stone bridge circuit. When a resistance of 6 Ω is connected in parallel to ‘S’ the bridge gets balanced . What is the value of ‘S’.
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 2 m when the cell is shunted by a 5 Ω resistance and is at a length 3 m when the cell is shunted by a 10 Ω resistance. The internal resistance of the cell is
The resistance 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 500 W heating unit is designed to operate from a 115 Volt line. If the line voltage drops to 110 volt. The percentage drop in heat output will be
When a battery sends current through a resistance R 1 for time ‘t’ , the heat produced in the resistor is Q. When the same battery sends current through another resistance R 2 for time ‘t’ , the heat produced in R 2 is again ‘Q’. The internal resistance of battery is
Which of the following plots may represent the thermal energy produced In a resistor for a given current as a function of time ?
A 100 W bulb B1 and two 60 W bulbs B2 and B3, are connected to a 250 V source, as shown in the figure. Now W1, W2 and W3 are the output powers of the bulb B1, B2 and B3 respectively. Then,
The change following through a resistance R varies with time ‘t’ as Q = at - bt 2 . The total heat produced in R is
A 25 W-120 V bulb and 100 W – 120 V bulb are connected in series across 120 V line. Which bulb will be brighter ?
The balancing length for a cell is 460 cm in a potential experiment. When an external resistance of 10 Ω is connected in parallel to the cell. The balancing length changes by 60 cm. If the internal resistance of the cell is N 10 , where N is an integer, the value of N is
In a meter bridge experiment S is a standard resistance. R is a resistance wire. It is found that balancing length is l = 25 cm . If ‘R’ is replaced by a wire of half length and same diameter that of R of same material. Then the balancing distance l in cm will now be
The series combination of two batteries both of the same emf 10 V , but different internal resistance of 20 Ω and 5 Ω is connected to the parallel combination of two resistors 25 Ω and R Ω .The voltage difference across the battery of internal resistance 20 Ω is zero . The value of R in Ω is,
A galvanometer whose resistance is 100 ohm has 25 divisions in it . When a current of 4 × 10 − 4 A passes through it, its needle (pointer) deflects by one division. To use this galvanometer as a voltmeter of range 2.5 V, it should be connected to a resistance of
In the experiment set up of meter bridge shown in the figure. The null point is obtained at a distance of 40 cm from A . If a 12 Ω resistor is connected in series with R 1 , the null point shifts by 10 cm. The resistance that should be connected in parallel with R 1 + 12 Ω such that the null point shifts back to initial position is
A milliammeter of range 120 mA and resistance 9 Ω is joined in a circuit as shown. The meter gives full scale deflection for current I when A and B are used as its terminal. i.e., current enters at A and leaves at ‘B’ [C is left isolated] .T he value of I is ……. A.
The voltmeter reads 40 V across resistance. The resistance of voltmeter is ………. Ohm
The current I 1 (in A) flowing through 1 Ω resistor in the following circuit is
In a building there are 15 Bulbs of 45 W, 15 bulbs of 100 W, 15 small fans of 10W and 2 heater of 1 kW. The voltage of electric main is 220V. the minimum fuse capacity (rated value) of the building will be:
The balancing length for a cell is 560 cm in a potentiometer experiment. When an external resistance of 10 Ω is connected in parallel to the cell, the balancing length changes by 60 cm. If the internal resistance of the cell is N 10 Ω , where N is an integer then value of N is
A galvanometer having a coil resistance 100 Ω gives a full scale deflection when a current of 1 mA is passed through it. What is the value of the resistance which can convert this galvanometer into a voltmeter giving full scale deflection for a potential difference of 10V?
Model a torch battery of length l to be made up of a thin cylindrical bar of radius ‘a’ and a concentric thin cylindrical shell of radius ‘b’ filled in between with an electrolyte of resistivity ρ (see figure). If the battery is connected to a resistance of value R, the maximum Joule heating in R will take place for :
Two resistors 400 Ω and 800 Ω are connected in series across a 6V battery. The potential difference measured by a voltmeter of 10 k Ω across 400 Ω resistor is close is :
A battery of 3.0 V is connected to a resistor dissipating 0.5 W of power. If the terminal voltage of the battery is 2.5 V, the power dissipated within the internal resistance is :
Four resistance 40 Ω , 60 Ω , 90 Ω and 110 Ω make the arms of a quadrilateral ABCD. Across AC is a battery of emf 40 V and internal resistance negligible. The potential difference across BD is V is
An electrical power line, having a total resistance of 2 Ω , delivers 1 k W a t 220 V . The efficiency of the transmission line is approximately.
In the circuit, given in the figure currents in different branches and value of one resistor are shown. Then potential at point B with respect to the point A is :
For maximum power delivered to the external circuit by the battery, the internal resistance of battery r (in Ω ) is
Two unknown resistances X and Y are connected to left and right gaps of a meter bridge and the balancing point is obtained 80cm from left when circuit is switched on. Now 10 ohm resistance is connected in parallel to X, it is observed that the balancing point is 50 cm from left when circuit is switched on. The values of X and Y respectively are
A resistance is shown in the figure. Its value and tolerance are given respectively by:
A milliammeter of range 10mA and resistance 9 Ω is joined in a circuit as shown. The meter gives full scale deflection for current i when A and B are used as its terminals, i.e., current enters at A and leaves at B. Find the value of i (in Amperes)
The figure shows a portion of a circuit. Resistor are known and indicated on diagram and voltmeters are identical. If voltmeters v 1 a n d v 2 reads 7.5V and 5V respectively then reading of v 3 .
What should be value of E for which galvanometer shows no deflection:
Two meters of voltage range 20.0 V and 30.0 V have to be constructed with a galvanometer. The resistance connected in series with the galvanometer is 1680 Ω for the 20.0 V range and 2930 Ω for the 30.0 V range. The resistance of the galvanometer and the full -scale current are respectively.
A potentiometer wire AB is 100 cm long and has a total resistance of 10 ohm. If the galvanometer shows zero deflection at the position C, then value of unknown resistance R is 2N Ω , then N is.
Electric bulb 50 W-100V glowing at full power are to be used in parallel with battery 120 V, 10 Ω . Find maximum number of bulbs that can be connected so that they glow in full power.
The heat generated in 5 Ω resistor due to current flowing through it is 10 cal per sec. The heat generated in 4 Ω resistor (in cal/sec) is
In the given circuit, the voltmeter and the electric cell are ideal. The reading of the voltmeter (in volt) is
Two resistances are connected in two gaps of a meter bridge. The balance point is 20cm from the zero end. A resistance of 15 Ω is connected in series with the smaller of the two. The null point shifts to 40cm. Then value of the smaller resistance is:
In a discharge tube when 200 V potential difference is applied 6.25 x 10 18 electrons move from cathode to anode and 3.125 x 10 18 singly charged positive ions move from anode to cathode in one second. Then the power of, tube (in W) is .
The error in measurement of unknown resistance of X is minimum in a meter bridge when l=70 cm, where l is the distance of null point from one end. If X = l ( A − l ) R find the value of A, where R is known resistance.
In an experiment, current measured is I = 10 . 0 A , potential difference measured is V = 100 . 0 V , length of the wire is 31 . 4 c m and the diameter of the wire is 2 . 00 m m (all in correct significant figures). Find resistivity of the wire in correct significant figures. [Take, π = 3 . 14 , (exact)]
If we use 100 Ω and 200 Ω in place of R and X we get null point deflection, l=33 cm . If we interchange the resistors, the null point length is found to be 67 cm. Find end corrections α and β .
In a meter bridge, null point is 20 cm, when the known resistance R is shunted by 10 Ω resistance, null point is found to be shifted by 10 cm. Find the unknown resistance X.
A resistance of 2 Ω is connected across one gap of a meter bridge (the length of the wire is 100 cm ) and an unknown resistance, greater than 2 Ω , is connected across the other gap. When these resistances are interchanged, the balance point shifts by 20 cm. Neglecting any corrections, the unknown resistance is
What are the maximum and minimum values of unknown resistance X , which can be determined using the post office box shown in the below figure?
Three resistances of 2 Ω each are connected to a 2V battery as shown in Fig. Then
An electric current flows through a non-uniform metal rod AB of length L with end A at x = 0 and end B at x = L. The current density J in the rod varies with x as shown in Fig. Which of the following statements is correct?
Figure shows a network of resistances connected to a 2V battery. If the internal resistance of the battery is negligible, current I in the circuit is
