Semiconductor Electronics: Materials, Devices and Simple Circuits Test 15

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Semiconductor Electronics: Materials, Devices and Simple Circuits Test 15

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Weekly Quiz Competition

Question 1
1 / -0

In which of the following statements, the obtained impure semiconductor is of p-type?

A
Germanium is doped with bismuth

B
Silicon is doped with antimony

C
Germanium is doped with gallium

D
Silicon is doped with phosphorus

Solution

A p-type semiconductor is produced by doping a 14 group element with a 13 group element as 14 group element has 4 valence electron whereas that of group 13 has 3 valence electron. We know that Germanium is a 14 group element and gallium is a 13 group element, thus doping germanium with gallium forms a p-type semiconductor.
Question 2
1 / -0

In intrinsic semiconductors:

A
$$n>p$$

B
$$p>n$$

C
$$n=p$$

D
$$n=0$$

Solution

Intrinsic semiconductors are pure ones. Hence there is no question of impurity. Valence band is the range of energy of electrons which are in the valence shell of the atoms of a substance. Conduction band is the range of energy of electrons which are free and available for conduction. At room temperature, some electrons of intrinsic semiconductors get excited and reach the conduction band. During this process, the electrons leave empty spaces in the valence shell. These empty spaces are known as holes in a semiconductor. Number of free electrons (n) is equal to the number of holes (p).
Question 3
1 / -0

The creation of voltage or electric current in a material upon exposure to light is termed as

A
photo-ionic effect

B
thermi-ionic effect

C
photo-voltaic effect

D
None of these.

Solution

The generation of current or voltage in a material, when exposed to light is called photovoltaic effect.
The device which operates on this effect is called photo-voltaic device or solar cell. It is a p-n junction diode which converts solar energy into electrical energy.
Question 4
1 / -0

In intrinsic semiconductors,:

A
holes or electrons are supplied by a foreign atom acting as an impurity

B
holes in the valence band are vacancies created by electrons that have been thermally excited to the conduction band

C
has high amount of impurities

D
none of the above

Solution

Intrinsic semiconductors are pure ones. Hence there is no question of impurity. Valence band is the range of energy of electrons which are in the valence shell of the atoms of a substance. Conduction band is the range of energy of electrons which are free and available for conduction. At room temperature, some electrons of intrinsic semiconductors get excited and reached the conduction band. During this process, the electrons leave empty spaces in the valence shell. These empty spaces are known as holes in a semiconductor.
Question 5
1 / -0

An intrinsic semiconductor is:

A
undoped

B
doped

C
can be undoped or doped

D
semi-doped

Solution

Doping is a process of adding impurities in a semiconductor. Doped semiconductors are known as extrinsic semiconductors and others are known as intrinsic ones
Question 6
1 / -0

LEDs have the following advantages over conventional incandescent low power lamps:

A
Long life and ruggedness.

B
Low operational voltage and less power

C
Fast on-off switching capability.

D
All of the above

Solution

LEDs have longer life as compared to incandescent lamps. LED require low operational voltage and less power as compared to incandescent lamps. LEDs also have fast on-off switching capabilities. So, the answer is (d) All of the above.
Question 7
1 / -0

Diode can work as

A
Modulator

B
Demodulator

C
Rectifier

D
Amplifier

Solution

Diode can work as rectifier, While converting $$AC$$ voltage to $$DC$$ voltage, we use $$4$$ diodes in the form of wheat stone bridge,It effectively works as rectifier.
Therefore option $$C$$ is correct
Question 8
1 / -0

In the valance band, the current is due to

A
the presence of electrons

B
the presence of holes

C
the presence of both electrons and holes

D
none of the above

Solution

In the valence band, current is only due to holes. In the conduction band, current is due to electrons.
Question 9
1 / -0

For one electron vacancy,

A
no holes are created

B
1 hole is created

C
2 holes are created

D
4 holes are created

Solution

For one electron vacancy, an empty space or void is created. In order to fill that empty space, a charge carrier with a charge equal in magnitude but opposite polarity should occupy that space in order to maintain electrical neutrality. Such a charge particle is called a hole.
Question 10
1 / -0

In N-type semiconductors, holes are:

A
majority carriers

B
minority carriers

C
absent

D
none of these

Solution

In an n-type semiconductor, i.e. doped with a pentavalent impurity, atoms have more number of electrons in the conduction band as compare to the number of holes in the valence band. So holes are in minority as compared to electrons which are in majority. So, holes are minority carriers.

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Semiconductor Electronics: Materials, Devices and Simple Circuits Test 15

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Semiconductor Electronics: Materials, Devices and Simple Circuits Test 15

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SHARING IS CARING

Question 1

Germanium is doped with bismuth

Silicon is doped with antimony

Germanium is doped with gallium

Silicon is doped with phosphorus

Solution

Question 2

$$n>p$$

$$p>n$$

$$n=p$$

$$n=0$$

Solution

Question 3

photo-ionic effect

thermi-ionic effect

photo-voltaic effect

None of these.

Solution

Question 4

holes or electrons are supplied by a foreign atom acting as an impurity

holes in the valence band are vacancies created by electrons that have been thermally excited to the conduction band

has high amount of impurities

none of the above

Solution

Question 5

undoped

doped

can be undoped or doped

semi-doped

Solution

Question 6

Long life and ruggedness.

Low operational voltage and less power

Fast on-off switching capability.

All of the above

Solution

Question 7

Modulator

Demodulator

Rectifier

Amplifier

Solution

Question 8

the presence of electrons

the presence of holes

the presence of both electrons and holes

none of the above

Solution

Question 9

no holes are created

1 hole is created

2 holes are created

4 holes are created

Solution

Question 10

majority carriers

minority carriers

absent

none of these

Solution

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