81.

Two batteries of emf 3V and 6 V with internal resistances 2 Ω and 4 Ω are connected in a circuit with resistance of 10 Ω as shown in figure. The current and potential difference between the points P and Q are

• $\frac{3}{16} \mathrm{A} \mathrm{and} \frac{8}{15} \mathrm{V}$

• $\frac{16}{3} \mathrm{A} \mathrm{and} \frac{15}{8} \mathrm{V}$

• $\frac{3}{16} \mathrm{A} \mathrm{and} 8 \mathrm{V}$

• $\frac{3}{16} \mathrm{A} \mathrm{and} \frac{15}{8} \mathrm{V}$

A rod made up of metal is 1.2 m long and 0.8 cm in diameter. Its resistance is 3.5 x 10^-3 Ω. Another disc made of the same metal is 2.0 cm in diameter and 1.25 mm thick. What is the resistance between the round faces of the disc?

• 1.35x 10^-8 Ω

• 2.70 x 10^-7 Ω

• 5.82 × 10^-7 Ω

• 8.10 × 10^-5 Ω

A body is moving along a rough horizontal surface with an initial velocity of 10 ms^-1.  If the body comes to rest after travelling a distance of 12m, then the coefficient of sliding friction will be

• 0.5

• 0.2

• 0.4

• 0.6

A galvanometer of resistance 25 Ω shows a deflection of 5 divisions when a current of 2 mA is passed through it. If a shunt of 4 Ω is connected and there are 20 divisions on the scale, then the range of the galvanometer is

• 1 A

• 58 A

• 58 mA

• 30 mA

The length of a given cylindrical wire is increased by 150%. Due to the consequent decrease in diameter the change in the resistance of the wire will be

• 200 %

• 525 %

• 300 %

• 400 %

The measurement of voltmeter in the following circuit is

• 2.25 V

• 4.25 V

• 2.75 V

• 6.25 V

A meter bridge is set-up as shown, to determine an unknown resistance X using a standard 10 ohm resistor. The galvanometer shows null point when tapping-key is at 52 cm mark. The end-corrections are 1 cm and 2 cm respectively for the ends A and B. The determined value of

• 10.2 ohm

• 10.6 ohm

• 10.8 ohm

• 11.1 ohm

A and B are two points on a uniform ring of resistance R. The ∠ ACB = 0, where C is the centre of the ring. The equivalent resistance between A and B is

In the circuit shown in figure, if A the diode forward voltage is 0.3 V, the voltage difference between A and B is

• 1.3 V

• 2.3 V

• 0

• 0.5 V

Assertion:  An electrical bulb starts glowing instantly as it is switched on. 

Reason:  Drift speed of electrons in a metallic wire is very large.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false