physics current

By increasing the temperature the resistance of a conductor

• increases.

• decreases.

• remains constant.

• initially increases then decreases.

A battery of emf V volts, resistance R1 & R2, a condenser C and switches S1 and S2 are connected in a circuit as shown in figure. The capacitor C gets fully charged to V volts when

• S1 & S2 are both closed

• S1 & S2 are both open

• S1 closed and S2 open

• S2 closed & S1 open.

The equivalent resistance of a circuit between A and B is

• 3 ohm

• 0

• 6 ohm

• 1.5 ohm

In the circuit shown in figure, the voltmeter reading would be

• 0 volt.

• 0.5 volt.

• 1 volt.

• 2 volt

The V-I graph for a conductor at temperatures T1 and T2 are as shown in the figure, (T2 – T1) is proportional to

• cos 2θ

• sin 2θ

• cot2θ

• tan 2θ

If a copper wire is stretched to make it 0.1 % longer. The percentage change in its resistance is

• 0.2% increase

• 0.2% decrease

• 0.1 % increase

• 0.1 % decrease

n the circuit shown in figure E1 = 7V, E2 = 7V R1 = R2 = 1 Ω and R3 = 3 Ω respectively. The current through the resistance R3 is

• 2A

• 3.5A

• 1.75A

• none of these

A cell of e.m.f E and internal resistance r is connected across a resistance r. The potential difference between the terminals of the cell must be

• E

• E/2

• E/4

• 3E/2

A conductor carries a current of 50mA if the area of cross-section of the conductor is 50 mm2 then value of the current density in Am-2 is

• 0.1

• 1

• 0.5

• 121

The drift velocity in the free electron is responsible for the?

• production of electric current

• None of these

• power dissipation

• production pf heat energy