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
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 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
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
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 :
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 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
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:
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:
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.
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 ?
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 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 ?
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
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
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
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.
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 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 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)
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.
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)]
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
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?