Electric Charges and Fields — Physics STD 12 Science — Question

The direction of induced current is such that it opposes the very cause that has produced it. This is the law of

(a) Lenz

(b) Faraday

(c) Kirchhoff

(d) Fleming

A body falling vertically downwards under gravity breaks in two parts of unequal masses. The centre of mass of the two parts taken together shifts horizontally towards:

1. Heavier piece.
2. Lighter piece.
3. Does not shift horizontally.
4. Depends on the vertical velocity at the time of breaking.

When an electric dipole   is placed in a uniform electric field   then at what angle between   and   the value of torque will be maximum

(a) 90°

(b) 0°

(c) 180°

(d) 45°

A steady current i flows in a small square loop of wire of side L in a horizontal plane. The loop is now folded about its middle such that half of it lies in a vertical plane. Let   and   respectively denote the magnetic moments due to the current loop before and after folding. Then

(a)	(b)  and   are in the same direction
(c)	(d)

According to Maxwell's equation, the velocity of light in any medium is expressed as.

Deviation of 5° is observed from a prism whose angle is small and whose refractive index is 1.5. The angle of prism is

(a) 7.5°

(b) 10°

(c) 5°

(d) 3.3°

When  undergoes fission, 0.1% of its original mass is changed into energy. How much energy is released if 1kg of   undergoes fission

(a) 9

(b) 9

(c) 9

(d) 9

For distance far away from centre of dipole the change in magnitude of electric field with change in distance from the centre of dipole is:

The vertical component of earth's magnetic field is zero at or The earth's magnetic field always has a vertical component except at the

(a) Magnetic poles

(b) Geographical poles

(c) Every place

(d) Magnetic equator

Materials suitable for permanent magnet, must have which of the following properties?