Electric Charges and Fields — Physics STD 12 Science — Question

In Milikan's oil drop experiment, a charged drop falls with terminal velocity V. If an electric field E is applied in vertically upward direction then it starts moving in upward direction with terminal velocity 2V. If magnitude of electric field is decreased to , then terminal velocity will become

(a)

(b) V

(c)

(d) 2V

The variation of the intensity of magnetisation (I) with respect to the magnetising field (H) in a diamagnetic substance is described by the graph

(a) OD

(b) OC

(c) OB

(d) OA

Let V and H be the vertical and horizontal components of earth's magnetic field at any point on earth. Near the north pole

(a) V >> H

(b) V << H

(c) V = H

(d) V = H = 0

Which among the following is the source of the magnetic field (magnetism)?

The amplification factor of a triode is 50. If the grid potential is decreased by 0.20 V, what increase in plate potential will keep the plate current unchanged

(a) 5 V

(b) 10 V

(c) 0.2 V

(d) 50 V

The bob of a simple pendulum is replaced by a magnet. The oscillations are set along the length of the magnet. A copper coil is added so that one pole of the magnet passes in and out of the coil. The coil is short-circuited. Then which one of the following happens

(a) Period decreases	(b) Period does not change
(c) Oscillations are damped	(d) Amplitude increases

Two parallel wires carrying currents in the same direction attract each other because of:

Only paraxial rays are used in image formation by spherical mirror; because this:

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”

In the figure a potential of + 1200 V is given to point A and point B is earthed, what is the potential at the point P

(a) 100 V

(b) 200 V

(c) 400 V

(d) 600 V