Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

A potentiometer wire has length 10 m and resistance 20Ω. A 2.5 V battery of negligible internal resistance is connected across the wire with an 80 Ω series resistance. The potential gradient on the wire will be

(a) 5

(b) 2.5

(c) 0.62

(d) 1

Equal charges are located at three corners of an equilateral triangle. The true statement for electric potential V and electric field intensity E at the centre O of the triangle will be:

The energy stored in a charged capacitor is:

If the equivalent resistance is to be increased, then the number of resistances should be connected in:

A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be

(a) Halved

(b) The same

(c) Doubled

(d) Quadrupled

A silver and zinc voltameter are connected in series and a current i is passed through them for a time t liberating W gm of zinc. The weight of silver deposited is nearly

(a) W

(b) 1.7 W

(c) 2.4 W

(d) 3.5 W

For a thermocouple, the temperature of inversion is that temperature at which thermo e.m.f. is

(a) Zero

(b) Maximum

(c) Minimum

(d) None of the above

Total internal reflection of light is possible when light enters from

(a) Air to glass

(b) Vacuum to air

(c) Air to water

(d) Water to air

Electromagnets are made of soft iron because soft iron has:

1. High retentivity and high coercive force.
2. High retentivity and low coercive force.
3. Low retentivity and high coercive force.
4. Low retentivity and low coercive force.