The resistance of an ammeter is 13 Ω and its scale is graduated for a current upto 100 A. After an additional shunt has been connected to this ammeter it becomes possible to measure currents upto 750 A by this meter. The value of
shunt resistance is

• 20 Ω

• 2 Ω

• 0.2 Ω

• 2 KΩ

272.

Three resistances P, Q, R each of 2Ω and an unknown resistance S form the four arms of a Wheatstone's bridge circuit. When a resistance of 6Ω is connected in parallel to S the bridge gets balanced. What is the value of S?

• 2 Ω

• 3 Ω

• 6 Ω

• 1 Ω

For a metallic wire, the ratio $\frac{\mathrm{V}}{\mathrm{i}}$ ( V = applied potential difference and i = current flowing) is

• independent of temperature

• increases as the temperature rises

• decreases as the temperature rises

• increases or decreases as temperature rises depending upon the metal 

A galvanometer having a resistance of 8 Ω is shunted by a wire of resistance 2 Ω.1f the total current is 1 A, the part of it passing through the shunt will be

• 0.25 A

• 0.8 A

• 0.2 A

• 0.5 A

At room temperature, copper has free electron density of 8.4 x 10²⁸ m^-3,  The electron drift velocity in a copper conductor of cross-section area of 10^-6 m² and carrying a current of 5.4 A will be

• 4 ms^-1

• 0.4 ms^-1

• 4 ms^-1

• 0.4 mm s^-1

A uniform wire of resistance R and length L is cut into four equal parts, each of length L/4, which are then connected in parallel combination. The effective resistance of the combination will be

• R

• 4 R

• $\frac{\mathrm{R}}{4}$

• $\frac{\mathrm{R}}{16}$

A capacitor of capacitance 5µF is connected as shown in the figure. The internal resistance of the cell is 0.5 Ω . The amount of charge on the capacitor plates is  

• 80 μC

• 40 μC

• 20 μC

• 10 μC

The equivalent resistance across A and B is     

• 2 Ω

• 3 Ω

• 4 Ω

• 5 Ω

In the circuit shown the value of I in ampere is

• 1

• 0.60

• 0.4

• 1.5

A current of 5A is passing through a metalic wire of cross-sectional area 4 × 10^-6 m² . If the density of charge carriers of the wire is 5 × 10²⁶ m^-3, then the drift velocity of the electrons will be

• 1 × 10² m/s

• 1.56 × 10^-2 m /s

• 1.56 × 10^-3 m/s

• 1 × 10^-2 m/s