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# Test: Types of Material of Semiconductor

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## 10 Questions MCQ Test Physics Class 12 | Test: Types of Material of Semiconductor

Test: Types of Material of Semiconductor for NEET 2023 is part of Physics Class 12 preparation. The Test: Types of Material of Semiconductor questions and answers have been prepared according to the NEET exam syllabus.The Test: Types of Material of Semiconductor MCQs are made for NEET 2023 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Types of Material of Semiconductor below.
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Test: Types of Material of Semiconductor - Question 1

### When a pure semiconductor is heated, its resistance:

Detailed Solution for Test: Types of Material of Semiconductor - Question 1

As temperature increases electrons from the valence band go to the conduction band, so conductivity increases hence resistance decreases.

Test: Types of Material of Semiconductor - Question 2

### What is the order of forbidden gap in the energy bands of silicon?​

Detailed Solution for Test: Types of Material of Semiconductor - Question 2

Silicon has a forbidden gap of 1.1 eV at 300 K temperature.

Test: Types of Material of Semiconductor - Question 3

### The densities of electrons and holes in an extrinsic semiconductor are 8 x 1015 cm-3 and 5 x 1012 cm-3 respectively. The mobilities of electrons and holes are respectively 23 x 103 cm3 / Vs and 102 cm3 / Vs. Which type of semiconductor is it?​

Detailed Solution for Test: Types of Material of Semiconductor - Question 3

It is an N-type semiconductor because the density of electrons is more here.

Test: Types of Material of Semiconductor - Question 4

A semiconductor is formed by:

Detailed Solution for Test: Types of Material of Semiconductor - Question 4
• The electrons surrounding each atom in a semiconductor are part of a covalent bond. A covalent bond consists of two atoms "sharing" a single electron.
• Each atom forms 4 covalent bonds with the 4 surrounding atoms. Therefore, between each atom and its 4 surrounding atoms, 8 electrons are being shared.
Test: Types of Material of Semiconductor - Question 5

Arrange the materials in ascending order of energy band gaps:

Detailed Solution for Test: Types of Material of Semiconductor - Question 5
• In the case of insulators, the energy gap is very large while in the case of conductors energy gap is very short.
• This energy gap refers to the energy difference between the valence band and conduction band whereas, in semiconductors, this band gap value is in between that of conductors and insulators.
Test: Types of Material of Semiconductor - Question 6

In a semiconductor, current conduction is due to:

Detailed Solution for Test: Types of Material of Semiconductor - Question 6

There are two types of semiconductors: p-type and n-type. Therefore both holes and electrons conduct current respectively.

Test: Types of Material of Semiconductor - Question 7

Electrons moving like molecules of gas exist in:

Detailed Solution for Test: Types of Material of Semiconductor - Question 7

Electrons in metal behave as gas.

Test: Types of Material of Semiconductor - Question 8

What is the value of the dielectric constant of air?

Detailed Solution for Test: Types of Material of Semiconductor - Question 8

The dielectric constant of a medium K = ∈/∈
where ∈ is the permittivity of the medium.
For air, ∈ = ∈0
⟹ K = 1

Test: Types of Material of Semiconductor - Question 9

Mobilities of electrons and holes in a sample of intrinsic germanium semiconductor at room temperature are 0.36m2/volt-sec and 0.17 m2/volt-sec respectively. If the electron and hole densities are each equal to 2.5 X 1019/m3, the conductivity is ______.​

Detailed Solution for Test: Types of Material of Semiconductor - Question 9

Given in question,

Mobilities of electrons μe ​= 0.36×m2V−1s−1

Mobilities of holes μh ​= 0.17×m2V−1s−1

densities of electron= densities of holes=2.5×1019m−3

As we know, conductivity,
σ=1/p​=e(μe​ne​+μn​nn​)
=1.6×10−19[0.36×2.5×1019+0.17×2.5×1019)]
=2.12Sm−1

So the electrical conductivity of germanium is 2.12Sm−1

Test: Types of Material of Semiconductor - Question 10

In a semiconductor, the forbidden energy gap between the valence band and conduction band is about​:

Detailed Solution for Test: Types of Material of Semiconductor - Question 10

In semiconductors, the forbidden gap between the valence band and conduction band is very small. It has a forbidden gap of about 1 electron volt (eV).

## Physics Class 12

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## Physics Class 12

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