Semiconductors and Insulators: A Comprehensive Guide for Mechanical Engineers

Question 1

Which type of doping creates a semiconductor with an excess of positive charge carriers?

Accepted Answer

Acceptor doping

Answer

Donor doping

Answer

Intrinsic doping

Answer

Extrinsic doping

Question 2

The resistivity of a semiconductor is:

Accepted Answer

Inversely proportional to its carrier concentration

Answer

Directly proportional to its carrier concentration

Answer

Independent of its carrier concentration

Answer

Cannot be determined without additional information

Question 3

The majority carriers in an N-type semiconductor are:

Accepted Answer

Electrons

Answer

Holes

Answer

Ions

Answer

Photons

Question 4

In semiconductors, the forbidden energy gap signifies:

Accepted Answer

The energy difference between the valence and conduction bands

Answer

The energy difference between the Fermi level and the valence band

Answer

The energy difference between the conduction band and the vacuum level

Answer

The energy difference between the conduction band and the forbidden band

Question 5

The primary purpose of doping semiconductors is to:

Accepted Answer

Increase their electrical conductivity

Answer

Decrease their electrical conductivity

Answer

Increase their thermal conductivity

Answer

Decrease their magnetic susceptibility

Question 6

An example of an n-type semiconductor is:

Accepted Answer

Silicon doped with arsenic

Answer

Silicon doped with boron

Answer

Germanium doped with gallium

Answer

Diamond doped with nitrogen

Question 7

Mobility of charge carriers in a semiconductor indicates:

Accepted Answer

Their average velocity under an applied electric field

Answer

Their charge-to-mass ratio

Answer

Their diffusion coefficient

Answer

Their recombination lifetime

Question 8

Which material is known for its high electrical resistance?

Accepted Answer

Polyethylene

Answer

Silicon

Answer

Copper

Answer

Aluminum

Question 9

The band gap of an insulator compared to a semiconductor is:

Accepted Answer

Larger

Answer

Smaller

Answer

Equal

Answer

Negative

Question 10

The dielectric constant of a material measures its:

Accepted Answer

Ability to store electrical energy

Answer

Ability to resist current flow

Answer

Ability to conduct heat

Answer

Ability to absorb sound

Question 11

What is the energy difference between the valence band and the conduction band in a semiconductor called?

Accepted Answer

Bandgap

Answer

Activation energy

Answer

Fermi energy

Answer

Ionization energy

Question 12

Which of the following materials is an example of an intrinsic semiconductor?

Accepted Answer

Pure silicon

Answer

Doped silicon

Answer

Gallium arsenide

Answer

Polycrystalline silicon

Question 13

What is the primary application of insulators in electronic devices?

Accepted Answer

Preventing the flow of electricity

Answer

Conducting electricity

Answer

Storing charge

Answer

Generating light

Question 14

Which of the following materials has the highest electrical resistivity?

Accepted Answer

Teflon

Answer

Copper

Answer

Aluminum

Answer

Water

Question 15

What type of bonding is responsible for the high electrical resistivity of insulators?

Accepted Answer

Covalent bonding

Answer

Ionic bonding

Answer

Metallic bonding

Answer

Van der Waals forces

Question 16

Which of the following is a common application of semiconductor diodes?

Accepted Answer

Rectification

Answer

Amplification

Answer

Oscillation

Answer

Energy storage

Question 17

What is the name of the phenomenon where a semiconductor material changes its conductivity when exposed to light?

Accepted Answer

Photoconductivity

Answer

Superconductivity

Answer

Piezoelectricity

Answer

Pyroelectricity

Question 18

How does doping semiconductors with group III and group V elements affect their electrical conductivity?

Accepted Answer

Group III doping creates holes, increasing conductivity.

Accepted Answer

Group V doping generates electrons, enhancing conductivity.

Answer

Both group III and group V doping decrease conductivity.

Question 19

At absolute zero temperature, all electrons in a semiconductor reside in the valence band. What does this imply about the material's electrical conductivity?

Accepted Answer

The material behaves as an insulator, as no electrons are available for conduction.

Answer

The material exhibits intermediate conductivity, with electrons shared between the valence and conduction bands.

Answer

The material acts as a conductor, with electrons freely moving in the conduction band.

Question 20

Adding a small amount of phosphorus to silicon creates an n-type semiconductor. What is the primary effect of this doping on the silicon's electrical properties?

Accepted Answer

Phosphorus atoms donate extra electrons, increasing the number of free charge carriers and enhancing conductivity.

Answer

Phosphorus creates electron vacancies (holes), leading to a p-type semiconductor with increased conductivity.

Answer

Phosphorus forms an insulating compound with silicon, reducing its conductivity.

Question 21

Which material is most suitable for use as an insulator in high-voltage applications due to its excellent electrical resistance and ability to withstand high voltages?

Accepted Answer

Ceramic

Answer

Germanium

Answer

Silicon

Answer

Copper

Question 22

A material with a band gap of 0.5 eV is classified as a:

Accepted Answer

Semiconductor

Answer

Superconductor

Answer

Conductor

Answer

Insulator

Question 23

In a p-type semiconductor, which type of charge carrier is primarily responsible for electrical conduction?

Accepted Answer

Holes

Answer

Protons

Answer

Electrons

Answer

Neutrons

Question 24

Which factor has a significant influence on the conductivity of a semiconductor, enabling it to transition from an insulator to a conductor?

Accepted Answer

Temperature

Answer

Malleability

Answer

Density

Answer

Boiling point

Question 25

The process of intentionally introducing impurities into a semiconductor to control its electrical properties is called:

Accepted Answer

Doping

Answer

Annealing

Answer

Sintering

Answer

Alloying

Question 26

In a semiconductor, the energy band located above the valence band and mostly empty at absolute zero is referred to as the:

Accepted Answer

Conduction band

Answer

Fermi level

Answer

Forbidden band

Answer

Valence band

Question 27

Which statement is NOT true about insulators?

Accepted Answer

They have a very small band gap.

Answer

They have high resistivity.

Answer

Electrons in insulators are tightly bound to their atoms.

Answer

They are poor conductors of electricity.

Question 28

The primary reason semiconductors are widely used in modern electronics is their:

Accepted Answer

Controllable electrical conductivity, enabling switching and signal processing.

Answer

Abundance and low cost, making them readily available for manufacturing.

Answer

High melting points, making them suitable for high-temperature applications.