Section 1 - Engineering Materials and Components

Question 1

Which of the following materials has the highest electrical conductivity at room temperature?

A. Aluminium

B. Copper

C. Silver

D. Gold

Question 2

The temperature coefficient of resistance of a pure metal conductor is:

A. Positive

B. Negative

C. Zero

D. Depends on the applied voltage

Question 3

Which of the following is a bad conductor of electricity?

A. Aluminium

B. Mercury

C. Copper

D. Rubber

Question 4

At absolute zero temperature, an intrinsic semiconductor behaves like a:

A. Perfect conductor

B. Perfect insulator

C. Metal

D. Superconductor

Question 5

The energy band gap of pure silicon at 300 K is approximately:

A. 0.7 eV

B. 1.1 eV

C. 1.4 eV

D. 5.5 eV

Question 6

The energy band gap of pure germanium at 300 K is approximately:

A. 0.5 eV

B. 0.7 eV

C. 1.1 eV

D. 1.4 eV

Question 7

Doping a pure semiconductor with a pentavalent impurity such as phosphorus produces:

A. A p-type semiconductor

B. An n-type semiconductor

C. An intrinsic semiconductor

D. An insulator

Question 8

In a p-type semiconductor, the majority carriers are:

A. Electrons

B. Holes

C. Both electrons and holes equally

D. Neither electrons nor holes

Question 9

The mobility of charge carriers in a semiconductor is defined as:

A. Drift velocity per unit electric field

B. Electric field per unit drift velocity

C. Current density per unit electric field

D. Charge per unit drift velocity

Question 10

Which of the following statements is true for a compensated semiconductor?

A. It contains only donor impurities

B. It contains only acceptor impurities

C. It contains both donor and acceptor impurities

D. It contains no impurities

Question 11

The Hall effect can be used to determine:

A. Only the sign of the majority carriers

B. Only the concentration of majority carriers

C. The sign, concentration, and mobility of majority carriers

D. Only the mobility of carriers

Question 12

The relative permittivity of vacuum is:

A. Zero

B. One

C. Infinity

D. Depends on the applied field

Question 13

The dielectric strength of a material is a measure of:

A. Its maximum operating temperature

B. The maximum electric field the dielectric can withstand without breakdown

C. The dielectric constant

D. The mechanical strength

Question 14

The unit of dielectric strength is:

A. Coulomb per metre

B. Volt per metre

C. Farad per metre

D. Ampere per metre

Question 15

Ferroelectric materials exhibit:

A. Spontaneous electric polarisation below a critical temperature

B. Spontaneous magnetisation below a critical temperature

C. Zero resistance below a critical temperature

D. No polarisation at any temperature

Question 16

Materials that are strongly attracted to a magnetic field are called:

A. Diamagnetic

B. Paramagnetic

C. Ferromagnetic

D. Non-magnetic

Question 17

Above the Curie temperature, a ferromagnetic material behaves as:

A. A diamagnetic material

B. A paramagnetic material

C. A superconductor

D. An antiferromagnetic material

Question 18

Soft magnetic materials are characterised by:

A. Wide hysteresis loop and high coercivity

B. Narrow hysteresis loop and low coercivity

C. Zero hysteresis and zero coercivity

D. Wide hysteresis loop and low remanence

Question 19

Ferrites are widely used as high-frequency core materials because they:

A. Have very high electrical conductivity

B. Have very high resistivity and reasonable permeability

C. Have very low permeability

D. Are perfect conductors

Question 20

A superconductor placed in a weak magnetic field below its critical temperature expels the magnetic flux from its interior. This is known as:

A. Hall effect

B. Meissner effect

C. Seebeck effect

D. Peltier effect

Question 21

Which of the following is not a property of a Type-I superconductor?

A. Zero electrical resistance below Tc

B. Perfect diamagnetism below Hc

C. Sharp transition to normal state at Hc

D. Two distinct critical magnetic fields Hc1 and Hc2

Question 22

Carbon composition resistors are commonly used because they are:

A. Highly accurate and stable

B. Inexpensive and available in a wide range of values

C. Suitable for very high power applications

D. Perfectly linear at all frequencies

Question 23

The capacitance of a parallel-plate capacitor increases when:

A. The distance between the plates is increased

B. The area of the plates is decreased

C. A dielectric of higher permittivity is inserted between the plates

D. The applied voltage is decreased

Question 24

Electrolytic capacitors are polarised and are mainly used in:

A. Radio-frequency tuning circuits

B. DC power-supply filtering

C. Precision timing circuits

D. Microwave circuits

Question 25

Which of the following is generally used as an insulator in high-voltage transmission lines?

A. Copper

B. Aluminium

C. Porcelain

D. Steel

Questions

Section 1 - Engineering Materials and Components - Set 1