Alternating Current — Physics STD 12 Science — Question

When a proton moves in a uniform magnetic field, the momentum change but its kinetic energy does not change because:

In a plano-convex lens the radius of curvature of the convex lens is 10 cm.  If the plane side is polished, then the focal length will be (Refractive index = 1.5)

(a) 10.5 cm

(b) 10 cm

(c) 5.5 cm

(d) 5 cm

The phenomenon of interference is shown by

(a) Longitudinal mechanical waves only	(b) Transverse mechanical waves only
(c) Electromagnetic waves only	(d) All the above types of waves

If the energy of a hydrogen atom in nth orbit is , then energy in the nth orbit of a singley ionized helium atom will be

(a) 4

(b)

(c) 2

(d)

A ball of mass 1 g and charge   moves from a point A. where potential is 600 volt to the point B where potential is zero. Velocity of the ball at the point B is 20 cm/s. The velocity of the ball at the point A will be

(a) 22.8 cm/s

(b) 228 cm/s

(c) 16.8 m/s

(d) 168 m/s

Nuclear fusion is common to the pair

(a) Thermonuclear reactor, uranium based nuclear reactor

(b) Energy production in sun, uranium based nuclear reactor

(c) Energy production in sun, hydrogen bomb

(d) Disintegration of heavy nuclei, hydrogen bomb

The primary origin (s) of magnetism lies in:

One can define ...A... of a place as the vertical plane which passes through the imaginary line joining the magnetic North and the South–poles.

Here, A refers to.

Two particles each of mass m and charge q are attached to the two ends of a light rigid rod of length 2R. The rod is rotated at constant angular speed about a perpendicular axis passing through its centre. The ratio of the magnitudes of the magnetic moment of the system and its angular momentum about the centre of the rod is

(a)

(b)

(c)

(d)