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

64.

Kirchhoff's law of junction, ΣI = 0, is based on

• conservation of energy

• conservation of charge

• conservation of energy as well as charge

• conservation of momentum

A battery of emf 10 V and internal resistance of 0.5 ohm is connected across a variable resistance R. The maximum value of R is given by

• 0.5 Ω

• 1.00 Ω

• 2.0 Ω

• 0.25 Ω

The internal resistance of a primary cell is 42. It generates a current of 0.2 A in an external resistance of 21 n. The rate at which chemical energy to consumed in providing current is

• 1 J/s

• 5 J/s

• 0.42 J/s

• 0.8 J/s

The equivalent resistance across A and B is

• 2 Ω

• 3 Ω

• 4 Ω

• 5 Ω

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-sectional area of 10^-6 m² and carrying a current of 5.4 A, will be

• 4 ms^-1

• 0.4 ms^-1

• 4 cm s^-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

• 4R

• $\frac{\mathrm{R}}{4}$

• $\frac{\mathrm{R}}{16}$

A 5 amp fuse wire can withstand a maximum power of 1 W in circuit. The resistance of the fuse wire is

• 0.2 Ω

• 5 Ω

• 0.4 Ω

• 0.04 Ω