Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

A cable of resistance 10 Ω carries electric power from a generator producing 250 kW at 10000 volt. The current in the cable is

(a) 25 A

(b) 250 A

(c) 100 A

(d) 1000 A

Conductivity of semiconductors:

Zener breakdown takes place if

(a) Doped impurity is low	(b) Doped impurity is high
(c) Less impurity in N-part	(d) Less impurity in P-type

1 tesla is equal to:

A small cylindrical soft iron piece is kept in a galvanometer so that

(a) A radial uniform magnetic field is produced

(b) A uniform magnetic field is produced

(c) There is a steady deflection of the coil

(d) All of these

The capacity of the parallel plate capacitor increases when:

Two wires A and B of same material and mass have their lengths in the ratio 1 : 2. On connecting them to the same source, the rate of heat dissipation in B is found to be 5W. The rate of heat dissipation in A is

(a) 10W

(b) 5W

(c) 20W

(d) None of these

There is an electric field E in X-direction. If the work done on moving a charge 0.2 C through a distance of 2 m  along a line making an angle 60°  with the X-axis is 4.0, what is the value of E

(a) N/C

(b) 4 N/C

(c) 5 N/C

(d) None of these

Internal forces can change:

1. The linear momentum but not the kinetic energy.
2. The kinetic energy but not the linear momentum.
3. Linear momentum as well as kinetic energy.
4. Neither the linear momentum nor the kinetic energy.

The triode constant is out of the following

(a) Plate resistance

(b) Amplification factor

(c) Mutual conductance

(d) All the above