Magnetism And Matter — Physics STD 12 Science — Question

A circular coil of diameter 7cm has 24 turns of wire carrying current of 0.75A. The magnetic moment of the coil is

(a) 6.9	(b) 2.3
(c)	(d)

The ratio of thermionic currents (I/I₀) for a metal when the temperature is slowly increased  to T as shown in figure. (I and I₀ are currents at T and respectively). Then which one is correct?

(a) A

(b) B

(c) C

(d) D

Two coherent sources of intensities, I₁ and I₂ produce an interference pattern. The maximum intensity in the interference pattern will be

(a) I1 + I2

(b)

(c) (I1 + I2)2

(d)

For electron moving in n^th orbit of H-atom the angular velocity is proportional to

(a) n

(b) 1/n

(c) n3

(d) 1/n3

A beam of light is converging towards a point I on a screen. A plane glass plate whose thickness in the direction of the beam = t, refractive index = μ, is introduced in the path of the beam. The convergence point is shifted by

(a) away

(b)  away

(c)  nearer

(d)  nearer

The free end of a simple pendulum is attached to the ceiling of a box. The box is taken to a height and the pendulum is oscillated. When the bob is at its lowest point, the box is released to fall freely. As seen from the box during this period, the bob will:

1. Continue its oscillation as before.
2. Stop.
3. Will go in a circular path.
4. Move on a straight line.

A thin oil layer floats on water. A ray of light making an angle of incidence of 40° shines on oil layer. The angle of refraction of light ray in water  is ()

(a) 36 .1°

(b) 44.5°

(c) 26. 8°

(d) 28.9°

The ionisation energy of 10 times ionised sodium atom is

(a) 13.6 eV

(b) 13.6 × 11 eV

(c)

(d) 13.6 × (11)2 eV

The maximum value of stopping potential in the following diagram is

(a) – 4V

(b) – 1V

(c) – 3V

(d) – 2V

A 5 ℃ rise in the temperature is observed in a conductor by passing some current. When the current is doubled, then rise in temperature will be equal to

(a) 5 ℃

(b) 10 ℃

(c) 20 ℃

(d) 40 ℃