Current Electricity

An electric bulb is rated 220 volt − 100 watt. The power consumed by it when operated on 110 volt will be

• 50 watt

• 75 watt

• 40 watt

• 40 watt

An inductor (L = 100 mH), a resistor (R = 100 Ω) and a battery (E = 100 V) are initially connected in series as shown in the figure. After a long time the battery is disconnected after short-circuiting the points A and B. The current in the circuit 1 mm after the circuit is

• 1 A

• 1/e A

• e A

• e A

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 AA /AB of their respective lengths must be

• 2

• 1

• 1/4

• 1/4

Two thin, long parallel wires separated by a distance  ‘d’ carry a current of ‘i’ A in the same direction. They will

• attract each other with a force of µ0i²/(2πd) 

• repel each other with a force of µ0i²/(2πd)

• attract each other with a force of µ0i²(2πd² )

• attract each other with a force of µ0i²(2πd² )

An energy source will supply a constant current into the load of its internal resistance is

• equal to the resistance of the load.

• very large as compared to the load resistance.

• zero

• zero

The total current supplied to the circuit by the battery is

• 1A

• 2 A

• 4 A

• 4 A

The resistance of the series combination of two resistances is S. When they are joined in parallel through total resistance is P. If S = nP, then the minimum possible value of n is

• 4

• 3

• 2

• 2

An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the length and radii of the wires are in the ratio of 4/3 and 2/3, then the ratio of the currents passing through the wire will be

• 3

• 1/3

• 8/9

• 8/9

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?

• 50 cm

• 80 cm

• 40 cm

• 40 cm

The electrochemical equivalent of a metal is 3.3 × 10⁻⁷ kg per coulomb. The mass of the metal liberated at the cathode when a 3 A current is passed for 2 seconds will be

• 19.8 × 10⁻⁷ kg

• 9.9 × 10⁻⁷ kg

• 6.6 × 10⁻⁷ kg

• 6.6 × 10⁻⁷ kg