Magnetism And Matter — Physics STD 12 Science — Question

Two important processes that occur during the formation of a p-n junction.

The particle that possesses half integral spin is:

Zener breakdown in a semi-conductor diode occurs when

(a) Forward current exceeds certain value	(b) Reverse bias exceeds certain value
(c) Forward bias exceeds certain value	(d) Potential barrier is reduced to zero

At a distance of 10 cm from a long straight wire carrying current, the magnetic field is 0.04 T. At the distance of 40 cm, the magnetic field will be

(a) 0.01 T

(b) 0.02 T

(c) 0.08 T

(d) 0.16 T

Which of the following combinations should be selected for better tuning of an LCR circuit used for communication?

A photosensitive substance emits _____when illuminated by light:

A man suffering from myopia can read a book placed at 10 cm distance. For reading the book at a distance of 60 cm with relaxed vision, focal length of the lens required will be

(a) 45 cm

(b) – 20 cm

(c) – 12 cm

(d) 30 cm

A metal plate gets heated, when cathode rays strike against, it due to

(a) Kinetic energy of cathode rays	(b) Potential energy of cathode rays
(c) Linear velocity of cathode rays	(d) Angular velocity of cathode rays

A ray of light is incident at an angle of 60° on one face of a prism of angle 30°. The ray emerging out of the prism makes an angle of 30° with the incident ray. The emergent ray is

(a) Normal to the face through which it emerges

(b) Inclined at 30° to the face through which it emerges

(c) Inclined at 60° to the face through which it emerges

(d) None of these

Plane of eddy currents makes an angle with the plane of magnetic lines of force equal to

(a) 40°

(b) 0°

(c) 90°

(d) 180°