The conduction band in a solid is partially filled at 0 k. The solid sample is

1

(a)

Conductor

(b)

Semiconductor

(c)

Insulator

(d)

none of these

In good conductorsof electricity the type of bonding that exists is

1

(a)

ionic

(b)

vander waals

(c)

covalent

(d)

(d)metallic

In intrinsic semiconductor at room temperature, the number of electrons and holes are

1

(a)

equal

(b)

zero

(c)

unequal

(d)

infinite

In an n-type semiconductor, the Fermi level lies 0.3 e V below the conduction band at 300 k. If the temperature is increased to 330 k, where does the new position of the Fermi level lie?

1

(a)

 0.55 e V below the conduction band

(b)

0.44 eV below the conduction band

(c)

0.33 eV below the conduction band

(d)

0.27 eV below the conduction band

According to energy band diagram, what makes a substance
(a) conductor 
(b) insulator?

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(a)

(a) Overlapping of conduction band and valence band
(b) A large energy gap (more than 3 eV) Between conduction band and valence band.

What is fermi level and fermi energy?

1

(a)

In an energy band, the highest energy level occupied by electron at 0K is called fermi level and its energy is called fermi -energy.

Where does the fermi-level of intrinsic semiconductor lie?

1

(a)

The fermi-level of intrinsic semiconductor lies mid way between its valence and conduction bands i.e., in the middle of forbidden energy gap of intrinsic semi-conductor.

What is doping?

1

(a)

Doping is a process of deliberate addition of a desirable impurity in a pure semiconductor to modify its properties in a controlled manner.

Name the types in which the electronic circuits have been classified.

1

(a)

(a) Analogue circuits and
(b) Digital circuits.

What is the order of energy gap in a conductor, semi conductor, and insulator?

1

(a)

Conductor - no energy gap
Semi Conductor - It is of the order of 1 ev
Insulator - 6 ev (or) more than 6 ev

Why does the conductivity of a semi conductor change with the rise in temperature ?

1

(a)

When a semi conductor is heated more & more electrons get enough energy to jump across the forbidden energy gap from valence band to the conduction band, where they are free to conduct electricity. Thereby increasing the conductivity of a semi conductor.

Is the number of electrons greater than, less than (or) equal to the number of holes in an intrinsic semi conductor?

1

(a)

In an intrinsic semi conductor the number of free electrons and holes is same.

Show in a energy band diagram the donor level for an N-type semi conductor.

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(a)

Draw in a energy band the acceptor level for a P-type semi conductor

1

(a)