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EC8252- ELECTRON DEVICES - UNIT 1

Total questions: 25

Worksheet time: 13mins

Name
Class
Date
1.

In a semiconductor which of the following carries can contribute to the current?

a)

Electrons

b)

Holes

c)

Both

d)

None

2.

Electrons from valence band rises to conduction band when the temperature is greater than 0 k. Is it True or False?

a)

True

b)

False

3.

The thermal equilibrium concentration of the electrons in the conduction band and the holes in the valence band depends upon?

a)

Effective density of states

b)

Fermi energy level

c)

Both A and B

d)

Neither A nor B

4.

In which of the following semiconductor, the concentration of the holes and electrons is equal?

a)

Extrinsic

b)

Compound

c)

Intrinsic

d)

None

5.

Single-element semiconductors are characterized by atoms with ____ valence electrons.

a)

2

b)

3

c)

4

d)

5

6.

There is a small amount of current across the barrier of a reverse-biased diode. This current is called as

a)

Reverse breakdown current

b)

Conventional current

c)

Reverse leakage current.

d)

Forward-bias current

7.

Doping of a semiconductor material is termed as

a)

adding of impurities to increase the resistance of the material.

b)

adding of impurities to hold the material together.

c)

adding of impurities to decrease the resistance of the material

d)

Removing of impurities to get pure silicon

8.

The term bias in electronics usually means

a)

the value of dc voltages for the device to operate properly.

b)

the value of ac voltage in the signal.

c)

the condition of current through a pn junction

d)

reverse saturation current in the pn junction

9.

Which is an example for Intrinsic semiconductor

a)

Gallium Arsenide

b)

Germanium

c)

Indium phosphate

d)

None of the above

10.

What types of impurity atoms are added to increase the number of conduction-band electrons in intrinsic silicon?

a)

octavalent

b)

pentavalent

c)

trivalent

d)

bivalent

11.

The most commonly used semiconductor material is

a)

Germanium

b)

Silicon

c)

Indium

d)

Phosphide

12.

An atom is made up of

a)

protons

b)

electrons

c)

neutrons

d)

all of the above

13.

The forward voltage across a conducting silicon diode is about

a)

0.6 V

b)

0.4 V

c)

0.3 V

d)

0.7 V

14.

Which statement best describes an insulator?

a)

A material with few free electrons

b)

A material doped to have some free electrons.

c)

A material with many free electrons.

d)

None of the above

15.

What is the difference between the practical value and theoretical value of ni?

a)

Factor of 3

b)

Factor of 2

c)

Factor of 4

d)

Factor of 1

16.

Holes in the n-type materials are called

a)

majority carriers

b)

minority carriers

c)

zero carriers

d)

None of the above

17.

When temperature increases intrinsic concentration increases which results increase in

a)

conductivity

b)

resistivity

c)

capacitance

d)

inductance

18.

Semiconductor material doped with trivalent impurity is called as

a)

p-type

b)

n-type

c)

neutral

d)

intrinsic

19.

Antimony is a

a)

trivalent impurity

b)

pentavalent impurity

c)

divalent impurity

d)

bivalent impurity

20.

In metals conductivity takes place due to

a)

Holes

b)

Free electrons

c)

Valence Electrons

d)

neutrons

21.
How many valence electrons are represented here?
a)
7
b)
5
c)
2
d)
8
22.
What is the maximum number of electrons that an orbital can have?
a)
1 electron
b)
2 electrons
c)
3 electrons
d)
4 electrons
23.
EM waves _______ travel the same speed in a vacuum. 
a)
never
b)
sometimes
c)
always
d)
can
24.

When electron jumps to conduction band,a vacancy is left in the

a)

conduction band

b)

nucleus

c)

valence band

d)

none of the above

25.

Copper and gold are good

a)

insulator

b)

conductor

c)

semiconductor

d)

None of the above