Semiconductor Physics and Diodes MCQs

Question 1

Depletion region in a pn junction diode consists of

Accepted Answer

Mobile donor and acceptor ions

Answer

Mobile donor ions

Answer

Mobile acceptor ions

Answer

Majority carriers

Question 2

When a diode is forward biased

Accepted Answer

Barrier potential decreases

Answer

Barrier potential increases

Answer

Majority current reduces

Answer

Minority current reduces

Question 3

Thw work function of a photo surface whose threshold wave length is 12,000 A, will be

Accepted Answer

1.03 eV

Answer

0.103 eV

Answer

0.673 eV

Answer

1.27 eV

Question 4

A potential difference is developed across a current carrying metal strip when the strip is placed in a transverse magnetic field. the above effect is known as

Accepted Answer

Hall's effect

Answer

Fermi's effect

Answer

Photo electric effect

Answer

Joule's effect

Question 5

As the temperature of a semi-conductor is reduced to absolute zero

Accepted Answer

all valance electrons tend to remain in the valaence band

Answer

all electrons become free

Answer

all electrons cease to move

Answer

all valance electrons shift to forbidden gap

Question 6

The crystal structure of silicon is

Accepted Answer

Diamond

Answer

Simple cubic

Answer

Body central cubic

Answer

Face centred cubic

Question 7

For insulators the energy gap is of the order of

Accepted Answer

5 to 15 eV

Answer

0.1 eV

Answer

0.7 eV

Answer

1.1 to 1.2 eV

Question 8

The photo electric threshold of tungsten is 2300 A. The energy of the electrons ejected from the surface by ultra-violet light of wavelength 1800 A, will be

Accepted Answer

1.5 eV

Answer

0.15 eV

Answer

150 eV

Answer

1.5 keV

Question 9

Barrier potential for silicon diode

Accepted Answer

0.7 V

Answer

0.3 V

Answer

0.4 V

Answer

0.1 V