Semiconductor Electronic: Material, Devices And Simple Circuits — Physics STD 12 Science — Question

In an electromagnetic wave.

At zero Kelvin a piece of germanium

(a) Becomes semiconductor	(b) Becomes good conductor
(c) Becomes bad conductor	(d) Has maximum conductivity

Energy released in fusion of 1 kg of deuterium nuclei

(a) 8

(b) 6

(c) 2

(d) 8

The velocity of light in a medium is half its velocity in air.  If ray of light emerges from such a medium into air, the angle of incidence, at which it will be totally internally reflected,   is

(a) 15o

(b) 30 o

(c) 45 o

(d) 60 o

Magnetic lines of force can pass through:

In a Young’s double slit experiment, the slit separation is 0.2 cm, the distance between the screen and slit is 1m. Wavelength of the light used is 5000 Å. The distance between two consecutive dark fringes (in mm) is

(a) 0.25

(b) 0.26

(c) 0.27

(d)  0.28

The image distance of an object placed 10 cm in front of a thin lens of focal length + 5 cm is

(a) 6.5 cm

(b) 8.0 cm

(c) 9.5 cm

(d) 10.0 cm

Which of the following describe that two lighter atoms combine to form one heavier atom?

The number of turns in the coil of an ac­ generator is 5000 and the area of the coil is . The coil is rotated at the rate of 100 cycles/sec in a magnetic field of 0.2. The peak value of the emf generated is nearly

(a) 786 kV

(b) 440 kV

(c) 220 kV

(d) 157.1 kV