Wave Optics — Physics STD 12 Science — Question

Two equal point charges are fixed at x = -a  and x = +a  on the x-axis. Another point charge Q is placed at the origin. The Change in the electrical potential energy of Q, when it is displaced by a small distance x along the x-axis, is approximately proportional to

(a) x

(b)

(c)

(d) 1/x

In a region of constant electric field, the field lines are _______.

A hollow metal sphere of radius 5cm is charged such that the potential on its surface is 10V. The potential at a distance of 2cm from the centre of the sphere

(a) Zero

(b) 10 V

(c) 4 V

(d) 10/3 V

A neutron, a proton, an electron and an α−particle enter a region of uniform magnetic field with equal velocities. The magnetic field is perpendicular to the plane of paper and directed into it. The tracks of particles are labeled in the figure. The neutron follows the track:

The work done in carrying a charge of 5μC  from a point A to a point B in an electric field is 10mJ.  The potential difference (  is then

(a) + 2kV

(b) – 2 kV

(c) + 200 V

(d) – 200 V

Two metal plates having charges Q, -Q face each other at some separation and are dipped into an oil tank. If the oil is pumped out, the electric field between the plates will:

1. Increase.
2. Decrease.
3. Remain the same.
4. Become zero.

Select the right option in the following

(a) Christian Huygens a contemporary of Newton established the wave theory of light by assuming that light waves were transverse

(b) Maxwell provided the compelling theoretical evidence that light is transverse wave

(c) Thomas Young experimentally proved the wave behaviour of light and Huygens assumption

(d) All the statements give above, correctly answers the question “what is light”

The Lenz's law is based on which of the following physical quantity?

One junction of a certain thermoelectric couple is at a fixed temperature  and the other junction is at temperature T. The thermo electromotive force for this is expressed by E = K(] . At temperature  the thermoelectric power is

(a)

(b)

(c)

(d)