286 + Mcqs in Electrical engineering material miscellaneous Page 1 McqOptions

1.	Consider the following functions: 1. To mask against diffusion or ion implant. 2. To act as a component in MOS devices. 3. To provide low resistivity paths. 4. To facilitate the entry of dopants. The functions of an oxide layer on a silicon wager would include:
A.	1 and 2
B.	2 and 3
C.	3 and 4
D.	1 and 4
Answer» B. 2 and 3

Discussion

2.	Which of the following elements act as donor impurities? 1. Gold 2. Phosphorus 3. Boron 4. Antimony 5. Arsenic 6. Indium Select the correct answer using the codes given below:
A.	1, 2 and 3
B.	1, 2, 4 and 6
C.	3, 4, 5 and 6
D.	2, 4 and 5
Answer» E.

Discussion

3.	The hysteresis loop of a magnetic material has an area of 5 cm2 with the scales given as 1 cm = 2 AT and 1 cm = 50 m Wb. At 50 Hz, the total hysteresis loss is:
A.	15 W
B.	20 W
C.	25 W
D.	50 W
Answer» D. 50 W

Discussion

4.	Which of the following statements relate to the Hall effect? 1. A potential difference is developed across a currentcarrying metal strip when the strip is placed in a transverse magnetic field. 2. The Hall effect is very weak in metals but is large in semiconductors. 3. The Hall effect is very weak in semiconductors but large in metals. 4. It is applied in the measurement of the magnetic field intensity.Select the correct answer using the codes given below:
A.	1, 2 and 3
B.	2 and 4
C.	1, 3 and 4
D.	1, 2 and 4
Answer» E.

Discussion

5.	Which of the following statements are correct? 1. Superconductors are amorphous thin films of Be, Bi and Fe. 2. Soft superconductors observe Silsbee s rule. 3. Hard superconductors observe high critical field and transition temperature.
A.	1 only
B.	1 and 2 only
C.	2 and 3 only
D.	1, 2 and 3
Answer» E.

Discussion

6.	Consider the following statements: Impurity diffusion is used in semiconductor to control the conductivity. The nature of the impurity profile should be such that the 1. impurity concentration decreases with diffusion depth. 2. profile results in an internal electric field. 3. impurity concentration is homogeneous with no internal electric field. Which of these statements are correct?
A.	1, 2 and 3
B.	1 and 3
C.	2 and 3
D.	1 and 2
Answer» E.

Discussion

7.	Consider the following statements: In a transformer, the core material should have low 1. coercivity 2. retentivity 3. permeability Which of these statements are correct?
A.	1 and 2
B.	2 and 3
C.	1 and 3
D.	1, 2 and 3
Answer» B. 2 and 3

Discussion

8.	Which of the following statements are correct for ceramic materials? 1. They are inorganic substances. 2. They are brittle. 3. They are good thermal insulators. Select the correct answer using the codes given below:
A.	1, 2 and 3
B.	1 and 2
C.	2 and 3
D.	1 and 3
Answer» B. 1 and 2

Discussion

9.	Consider the following statements: The dielectric constant of an insulator depends on 1. applied voltage. 2. frequency of the alternating field applied. 3. temperature. 4. maximum current density in the insulator. Select the correct answer using the codes given below:
A.	1 and 2
B.	1 and 3
C.	2 and 3
D.	3 and 4
Answer» D. 3 and 4

Discussion

10.	Electron mobility and life-time in a semiconductor at room temperature are respectively 0.36m2/(Vs) and 340 s. The diffusion length is:
A.	3.13 mm
B.	1.77 mm
C.	3.55 mm
D.	3.13 cm
Answer» C. 3.55 mm

Discussion

11.	For which of the following semiconductors, resistance does not follow Ohm s law over some specific range of the applied voltage? 1. Germanium 2. Gallium arsenide 3. Iridium phosphide Select the correct answer using the codes given below:
A.	1, 2 and 3
B.	1 and 2
C.	2 and 3
D.	1 and 3
Answer» D. 1 and 3

Discussion

12.	Which of the following are the properties of ferromagnetic domains? 1. Permanent magnetisation. 2. Atomic moments in individual domains are all aligned neither parallel to nor perpendicular to one another below Curie point temperature. 3. Each domain is magnetically saturated. 4. Above Curie temperature, domains disrupt. Select the correct answer using the codes given below:
A.	1 and 3
B.	2 and 4
C.	1, 3 and 4
D.	3 and 4
Answer» D. 3 and 4

Discussion

13.	Consider the following materials: 1. Nickel 2. Silver 3. Oxygen 4. Aluminium The correct sequence of these materials in decreasing order of their magnetic permeability is:
A.	1, 4, 3, 2
B.	1, 4, 2, 3
C.	4, 1, 3, 2
D.	4, 1, 2, 3
Answer» C. 4, 1, 3, 2

Discussion

14.	The conductivity of a metal at ultraviolet frequency (1014 Hz) approximately equals:
A.	infinity
B.	zero
C.	dc conductivity
D.	half of dc conductivity
Answer» B. zero

Discussion

15.	If the molecular structure and density of the material are known, then which of the following material parameters may be determined from the r versus 1/T plot?
A.	Sum of electronic and ionic polarizabilities
B.	Lattice constant
C.	Breakdown voltage
D.	Loss tangent
Answer» B. Lattice constant

Discussion

16.	Consider the following statements: The energy band gap of GaAs 1. is indirect. 2. is direct. 3. is 1.43 eV. 4. corresponds to wavelength of 0 89 m. (Given h = 6.63 10 34 joule-sec) Of these the correct statements is/are:
A.	1 alone
B.	2, 3 and 4
C.	2 and 3
D.	1 and 4
Answer» C. 2 and 3

Discussion

17.	Which of the following crystallographic defects contribute to electronic defects? 1. Thermal vibration 2. Point defects 3. Line defects 4. Surface defects Select the correct answer using the codes given belowCodes:
A.	1, 2 and 3
B.	2, 3 and 4
C.	1, 3 and 4
D.	1, 2 and 4
Answer» C. 1, 3 and 4

Discussion

18.	Some of the characterizing parameters of a material are: 1. magnetic permeability. 2. electron relaxation time. 3. electron effective mass. 4. energy band gap. In case of metals, increase in one of the above parameters decreases its conductivity, while increase in another increases the conductivity. These two parameters are repectively:
A.	1 and 3
B.	3 and 2
C.	4 and 3
D.	1 and 2
Answer» C. 4 and 3

Discussion

19.	Consider the following statements: Superconductivity in a material can be destroyed by 1. increasing the temperature above a certain limit. 2. applying a magnetic field above a certain limit. 3. passing a current, above a certain limit, through the material. 4. increasing the current to a point above the critical current. Of these the correct statements are:
A.	2, 3 and 4
B.	1, 3 and 4
C.	1, 2 and 3
D.	1, 2 and 4
Answer» E.

Discussion

20.	The following figure gives the schematic arrangement of spins of four different types of magnetic materials: The ferromagnetic and ferrimagnetic materials refer to arrangements given in fig.
A.	I and II respectively
B.	II and III respectively
C.	I and III respectively
D.	II and IV respectively
Answer» E.

Discussion

21.	Which of the following pair(s) is/are correctly matched? Material Application (A) Rochelle salt Phonograph (B) Barium titanate Amplifier (C) Quartz Oscillator. Select the correct answer using the codes given below:
A.	only 2
B.	1 and 2
C.	1 and 3
D.	2 and 3
Answer» D. 2 and 3

Discussion

22.	A paramagnetic material is used in an energy conversion process in which the following events occur: 1. Thermal energy is generated. 2. Dipoles are turned. 3. Magnetic field is generated. 4. Material reacts to oppose it. The correct sequence of these events is:
A.	3, 4, 2, 1
B.	1, 4, 2, 3
C.	1, 2, 4, 3
D.	3, 2, 4, 1
Answer» E.

Discussion

23.	Consider the following metals: 1. Zinc 2. Gold 3. Silver 4. Copper The correct sequence of the increasing order of their resistivities is:
A.	4, 3, 1, 2
B.	3, 4, 2, 1
C.	4, 3, 2, 1
D.	3, 4, 1, 2
Answer» C. 4, 3, 2, 1

Discussion

24.	Some magnetic materials may be classified on the basis of: 1. susceptibility 2. saturation 3. spin arrangement 4. nature of hysteresis 5. domain structure 6. critical temperature above which it behaves as a paramagnetic material. Out of these, those which can be used to distinguish between ferrite and ferromagnetic materials would include:
A.	1, 3 and 4
B.	2, 3 and 6
C.	3, 4 and 5
D.	3, 5 and 6
Answer» B. 2, 3 and 6

Discussion

25.	A type I superconductor maintained at a temperature T < Tc is subjected to a magnetic field H < Hc the superconductor will exhibit:
A.	perfect diamagnetism
B.	partial diamagnetism
C.	perfect paramagnetism
D.	partial paramagnetism
Answer» B. partial diamagnetism

Discussion

26.	If a material is a glass, then you know it must:
A.	contain silica (SiO
B.	)
C.	be a ceramic, since all ceramics are glass and glass is a kind of ceramic
D.	have a monoclinic crystal structure
E.	have no long-range crystalline lattice structure
Answer» E. have no long-range crystalline lattice structure

Discussion

27.	The Wiedemann-Franz law states that the ratio of thermal conductivity to electrical conductivity for a material is approximately constant, independent of the material for a fixed temperature. Moreover, as temperature changes, the ratio of thermal conductivity to electrical conductivity for a material is directly proportional to the temperature of the material. Which of the following is true of the Wiedemann-Franz law? (i) The Wiedemann-Franz law applies only to ceramics and plastics. (ii) The Wiedemann-Franz law applies best to elemental metals. (iii) The Wiedemann-Franz law is based on the free electron theory of metals, in which both thermal energy andelectrical charge are transported primarily by free electrons. (iv) The Wiedemann-Franz law is based on the Pauling s rules for electronegativity, in which the electrical conductivity and thermal conductivity of ceramic and plastic materials are related to the percentage of ionicity of the atomic bonds in the structure.
A.	(i) only
B.	(ii) only
C.	(ii) and (iii)
D.	(i), (ii), (iii) and (iv)
Answer» D. (i), (ii), (iii) and (iv)

Discussion

28.	Some of the characterising parameters of a materials are: 1. magnetic permeability 2. electron relaxation time 3. electron effective mass 4. energy band gap In case of metals, increase in one of the above parameters decreases its conductivity, while increase in anotherincreases the conductivity. These two parameters are respectively:
A.	1 and 3
B.	3 and 2
C.	4 and 3
D.	1 and 2
Answer» C. 4 and 3

Discussion

29.	Consider the following statements: In the case of diamagnetic materials, the magnetic susceptibility is : 1. positive 2. negative 3. independent of temperature4. inversely proportional to temperature Of these statements:
A.	1 and 3 are correct
B.	2 and 3 are correct
C.	1 and 4 are correct
D.	2 and 4 are correct
Answer» C. 1 and 4 are correct

Discussion

30.	Eg of a semiconductor:
A.	increases with temperature
B.	is invariant with temperature
C.	decreases with temperature
D.	All of the above
Answer» D. All of the above

Discussion

31.	The charge of a hole is x C, where x is equal to:
A.	1.6 10
B.	1.6 10
C.
D.	1.6
E.	None of these
Answer» C.

Discussion

32.	Which of the following statements are true: 1. LEDs fabricated from GaAs emit radiation in the ultraviolet region. 2. LEDs fabricated from GaAs emit radiation in the infra red region. 3. When a semiconductor is doped with pentavalent impurity, the resulting material is p-type. 4. A n-type semiconductor is electrically neutral.
A.	1 and 2 only
B.	3 and 4 only
C.	2 and 3 only
D.	1, 2, 3 and 4
Answer» B. 3 and 4 only

Discussion

33.	Which of the following pairs are correctly matched? 1. Steatite:Magnesia-silica ceramic dielectric resistivity2. Discharge:Gas bubbles are responsible breakdown for it3. Dielectric loss:It decreases with decrease in humidity4. FerroelectricCurie temperature:It is related to both ferromagnetic and ferroelectric materialsSelect the correct answer using the codes given below:
A.	2, 3 and 4
B.	1, 3 and 4
C.	1 and 3
D.	1, 2 and 4
Answer» E.

Discussion

34.	The microstructure composition of pearlite for an Fe3C diagram consists of:
A.	carbon dissolved in alpha iron having a body centred cubic structure
B.	carbon dissolved in gamma iron having a bodycentred cubic structure
C.	a mixture of body-centred alpha having a facecentred gamma iron
D.	carbon dissolved in body-centred alpha iron and an Fe
E.	C compound of higher carbon
Answer» E. C compound of higher carbon

Discussion

35.	Semiconductors have electrical conductivities of the following order (ohm-cm 1):
A.	10
B.	10
C.
D.	10
E.	10
Answer» C.

Discussion

36.	A high Tc superconductor has the transition temperature around:
A.	400 K
B.	90 K
C.	20 K
D.	4 K
Answer» E.

Discussion

37.	Which of the following pairs are correctly matched? 1. Nordheim equation:Effect of alloying on resistivity2. Lorentz number: h T2 43. Wiedemana-Franz law:ne >> nh4. Matthilssen rule:Total resistivity in the sum of different effects Select the correct answer using the codes given below:
A.	2 and 3
B.	1 and 4
C.	1 and 2
D.	1, 2 and 4
Answer» C. 1 and 2

Discussion

38.	Bond formation in dry ice (solid CO2) is due to:
A.	Vander Waals force
B.	Electrostatic force
C.	Newton s force
D.	Hydrogen bond
Answer» B. Electrostatic force

Discussion

39.	In the above question, the potential energy at infinity will be equal to:
A.
B.
C.
D.	zero
E.	a constant finite value
Answer» D. zero

Discussion

40.	If Coulomb s attractive force is ofAr2 form in a material system, its potential energy will be given by:
A.
B.
C.
Answer» C.

Discussion

41.	Resistance R of intrinsic semiconductor is:
A.	T K
B.	T K
C.	= R
D.
Answer» E.

Discussion

42.	A material having different properties in different directions is known as:
A.	isotropic
B.	anisotropic
C.	crystalline
D.	metal
Answer» C. crystalline

Discussion

43.	A material has forbidden energy gap Eg = 1 eV, between valence and conduction bands. Such a material will behave as:
A.	a good conductor
B.	an insulator
C.	a semiconductor
D.	a varactor
Answer» C. a semiconductor

Discussion

44.	The residual resistivity of metals:
A.	is essentially independent of temperature
B.	increases linearly with increasing temperature
C.	increases linearly with increasing temperature
D.	initially increases linearly with temperature and then remains constant
Answer» B. increases linearly with increasing temperature

Discussion

45.	Which one of the following polarisation mechanisms l sets of mechanisms contribute(s) to the static dielectric constant of a homopolar neutral dielectric?
A.	Electronic
B.	Electric and ionic
C.	Electronic, ionic and dipolar
D.	Electronic and dipolar
Answer» D. Electronic and dipolar

Discussion

46.	Ferrities have:
A.	low copper loss
B.	low eddy current loss
C.	low resistivity
D.	higher specific gravity compared to iron
Answer» D. higher specific gravity compared to iron

Discussion

47.	In an extrinsic semiconductor, the Hall coefficient RH:
A.	increases with increase of temperature
B.	decreases with increase of temperature
C.	is independent of the change of temperature
D.	changes with the change of magnetic field
Answer» C. is independent of the change of temperature

Discussion

48.	Fermions are the particles, which obey:
A.	Maxwell-Boltzmann s statistics
B.	Bose-Einstein s statistics
C.	Heisenberg s uncertainty principle
D.	Pauli s exclusion principle
Answer» E.

Discussion

49.	In a degenerate semiconductor, the majority carriers are controlled by:
A.	Fermi-Dirac statistics
B.	Maxwell-Boltzmann statistics
C.	Bose-Einstein (B E) statistics
D.	Pauli s exclusion principle
Answer» B. Maxwell-Boltzmann statistics

Discussion

50.	Which one of the following is an essential components of electromechanical relays?
A.	Graphite rod
B.	LED
C.	An electromagnet
D.	MOSFET
Answer» D. MOSFET

Discussion

Explore topic-wise MCQs in Electrical Engineering materials.

Consider the following functions: 1. To mask against diffusion or ion implant. 2. To act as a component in MOS devices. 3. To provide low resistivity paths. 4. To facilitate the entry of dopants. The functions of an oxide layer on a silicon wager would include:

Which of the following elements act as donor impurities? 1. Gold 2. Phosphorus 3. Boron 4. Antimony 5. Arsenic 6. Indium Select the correct answer using the codes given below:

The hysteresis loop of a magnetic material has an area of 5 cm2 with the scales given as 1 cm = 2 AT and 1 cm = 50 m Wb. At 50 Hz, the total hysteresis loss is:

Which of the following statements are correct? 1. Superconductors are amorphous thin films of Be, Bi and Fe. 2. Soft superconductors observe Silsbee s rule. 3. Hard superconductors observe high critical field and transition temperature.

Consider the following statements: In a transformer, the core material should have low 1. coercivity 2. retentivity 3. permeability Which of these statements are correct?

Which of the following statements are correct for ceramic materials? 1. They are inorganic substances. 2. They are brittle. 3. They are good thermal insulators. Select the correct answer using the codes given below:

Consider the following statements: The dielectric constant of an insulator depends on 1. applied voltage. 2. frequency of the alternating field applied. 3. temperature. 4. maximum current density in the insulator. Select the correct answer using the codes given below:

Electron mobility and life-time in a semiconductor at room temperature are respectively 0.36m2/(Vs) and 340 s. The diffusion length is:

For which of the following semiconductors, resistance does not follow Ohm s law over some specific range of the applied voltage? 1. Germanium 2. Gallium arsenide 3. Iridium phosphide Select the correct answer using the codes given below:

Consider the following materials: 1. Nickel 2. Silver 3. Oxygen 4. Aluminium The correct sequence of these materials in decreasing order of their magnetic permeability is:

The conductivity of a metal at ultraviolet frequency (1014 Hz) approximately equals:

If the molecular structure and density of the material are known, then which of the following material parameters may be determined from the r versus 1/T plot?

Consider the following statements: The energy band gap of GaAs 1. is indirect. 2. is direct. 3. is 1.43 eV. 4. corresponds to wavelength of 0 89 m. (Given h = 6.63 10 34 joule-sec) Of these the correct statements is/are:

Which of the following crystallographic defects contribute to electronic defects? 1. Thermal vibration 2. Point defects 3. Line defects 4. Surface defects Select the correct answer using the codes given belowCodes:

The following figure gives the schematic arrangement of spins of four different types of magnetic materials: The ferromagnetic and ferrimagnetic materials refer to arrangements given in fig.

Which of the following pair(s) is/are correctly matched? Material Application (A) Rochelle salt Phonograph (B) Barium titanate Amplifier (C) Quartz Oscillator. Select the correct answer using the codes given below:

A paramagnetic material is used in an energy conversion process in which the following events occur: 1. Thermal energy is generated. 2. Dipoles are turned. 3. Magnetic field is generated. 4. Material reacts to oppose it. The correct sequence of these events is:

Consider the following metals: 1. Zinc 2. Gold 3. Silver 4. Copper The correct sequence of the increasing order of their resistivities is:

A type I superconductor maintained at a temperature T < Tc is subjected to a magnetic field H < Hc the superconductor will exhibit:

If a material is a glass, then you know it must:

Consider the following statements: In the case of diamagnetic materials, the magnetic susceptibility is : 1. positive 2. negative 3. independent of temperature4. inversely proportional to temperature Of these statements:

Eg of a semiconductor:

The charge of a hole is x C, where x is equal to:

The microstructure composition of pearlite for an Fe3C diagram consists of:

Semiconductors have electrical conductivities of the following order (ohm-cm 1):

A high Tc superconductor has the transition temperature around:

Which of the following pairs are correctly matched? 1. Nordheim equation:Effect of alloying on resistivity2. Lorentz number: h T2 43. Wiedemana-Franz law:ne &gt;&gt; nh4. Matthilssen rule:Total resistivity in the sum of different effects Select the correct answer using the codes given below:

Bond formation in dry ice (solid CO2) is due to:

In the above question, the potential energy at infinity will be equal to:

If Coulomb s attractive force is ofAr2 form in a material system, its potential energy will be given by:

Resistance R of intrinsic semiconductor is:

A material having different properties in different directions is known as:

A material has forbidden energy gap Eg = 1 eV, between valence and conduction bands. Such a material will behave as:

The residual resistivity of metals:

Which one of the following polarisation mechanisms l sets of mechanisms contribute(s) to the static dielectric constant of a homopolar neutral dielectric?

Ferrities have:

In an extrinsic semiconductor, the Hall coefficient RH:

Fermions are the particles, which obey:

In a degenerate semiconductor, the majority carriers are controlled by:

Which one of the following is an essential components of electromechanical relays?

Which of the following pairs are correctly matched? 1. Nordheim equation:Effect of alloying on resistivity2. Lorentz number: h T2 43. Wiedemana-Franz law:ne >> nh4. Matthilssen rule:Total resistivity in the sum of different effects Select the correct answer using the codes given below: