286 + Mcqs in Electrical engineering material miscellaneous Page 3 McqOptions

101.	Which of the following statements relate to the Hall effect?
A.	1, 2 and 3
B.	2 and 4
C.	1, 3 and 4
D.	1, 2 and 4
Answer» E.

Discussion

102.	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
A.	1, 2 and 3
B.	1 and 3
C.	2 and 3
D.	1 and 2
Answer» E.

Discussion

103.	The conductivity of a semiconductor crystal due to any current carrier is NOT proportional to:
A.	mobility of the carrier
B.	effective density of states in the conduction band
C.	electronic charge
D.	surface states in the semiconductor
Answer» E.

Discussion

104.	Consider the following statements: In a transformer, the core material should have low
A.	1 and 2
B.	2 and 3
C.	1 and 3
D.	1, 2 and 3
Answer» B. 2 and 3

Discussion

105.	Gold, which has an atomic radius of 0.144 nm, crystallizes in a FCC structure. The lattice parameter of gold is:
A.	the same as the atomic radius
B.	0.407 nm
C.	0.333 nm
D.	0.576 nm
Answer» C. 0.333 nm

Discussion

106.	When a semiconductor bar is heated at one end, a voltage across the bar is developed. If the heated end is positive, the semiconductor is:
A.	p-type
B.	n-type
C.	Intrinsic
D.	Highly degenerate
Answer» C. Intrinsic

Discussion

107.	When copper is added to silver in small quantity so as to form an alloy, the resistivity of such an alloy is:
A.	equal to the resistivity of copper
B.	equal to the resistivity of silver
C.	greater than the resistivity of copper
D.	in between the resistivity of silver and copper
Answer» D. in between the resistivity of silver and copper

Discussion

108.	When BCC iron is heated, it charges to FCC iron resulting in:
A.	contraction in volume
B.	increase in volume
C.	no change in volume
D.	crack in the material
Answer» B. increase in volume

Discussion

109.	A fine powder of a refractory metal may be added to a molten metal prior to solidification of the metal. The fine powder may act to:
A.	produce a single crystal. This is called a Czochalski technique.
B.	induce homogeneous nucleation in the molten metal
C.	reduce the average grain size of the final, solidified metal
D.	produce large numbers of moving dislocations in the crystal
Answer» D. produce large numbers of moving dislocations in the crystal

Discussion

110.	Hall effect device can be used to:
A.	multiply two signals
B.	divide one signal by another on an instantaneous basis
C.	add two signals
D.	Subtract one signal from another
Answer» B. divide one signal by another on an instantaneous basis

Discussion

111.	Electron mobility and life-time in a semiconductor at room temperature are respectively 0.36m
A.	3.13 mm
B.	1.77 mm
C.	3.55 mm
D.	3.13 cm
Answer» C. 3.55 mm

Discussion

112.	For which of the following semiconductors, resistance does not follow Ohm s law over some specific range of the applied voltage?
A.	1, 2 and 3
B.	1 and 2
C.	2 and 3
D.	1 and 3
Answer» D. 1 and 3

Discussion

113.	Consider the following statements: The dielectric constant of an insulator depends on
A.	1 and 2
B.	1 and 3
C.	2 and 3
D.	3 and 4
Answer» D. 3 and 4

Discussion

114.	Ferromagnetics owe their properties to:
A.	Filled inner sub-shells
B.	Vacant inner sub-shells
C.	Partially filled inner sub-shells
D.	All the sub-shells equally filled
Answer» D. All the sub-shells equally filled

Discussion

115.	The temperature at or above which a ferromagnetic material becomes paramagnetic is called:
A.	Critical temperature
B.	Inversion temperature
C.	Curie temperature
D.	Debye temperature
Answer» D. Debye temperature

Discussion

116.	Which of the following statements are correct for ceramic materials?
A.	1, 2 and 3
B.	1 and 2
C.	2 and 3
D.	1 and 3
Answer» B. 1 and 2

Discussion

117.	For a medium carbon steel, having a 0.50% carbon content, slow cooling of austenite will cause austenite to transform to carbide and ferrite. Rapid quenching of austenite can result in:
A.	formation of martensite, which produces a very hard and brittle steel
B.	retention of austenite, even at room temperature which gives a very ductile and tough steel
C.	formation of large carbide particles near the grain boundaries in the steel, which makes the steel brittle but very tough
D.	retention of austenite, even at room temperature, which gives a very brittle and hard steel
Answer» B. retention of austenite, even at room temperature which gives a very ductile and tough steel

Discussion

118.	The effect of temperature on the strength of linear thermoplastics is that:
A.	as the temperature of thermoplastics increases, they cure by cross-linking and forming a three-dimensional network of covalent bonds, increasing the strength of the thermoplastic
B.	same effect as (a), except that as the temperature gets sufficiently high, the covalently, bonded network weakens and eventually burns
C.	nothing happens. Temperature doesn t affect thermoplastics
D.	as the temperature of thermoplastics is increased, the secondary atomic bonds weaken and the material softens
Answer» E.

Discussion

119.	In the selection of an opaque surface to act as collector of solar energy. It would be desirable for the surface to have which of the following sets of characteristics?
A.	Absorptivity for radiation in the visible spectrum = high emissivity for low temperature radiation = low convective heat transfer coefficient = low
B.	Absorptivity for radiation in the visible spectrum = high emissivity for low temperature radiation = high convective heat transfer coefficient = low
C.	Absorptivity for radiation in the visible spectrum = low emissivity for low temperature radiation = high convective heat transfer coefficients = high
D.	Absorptivity for radiation in the visible spectrum = low emmissivity for low temperature radiation = high convective heat transfer coefficient = low
Answer» B. Absorptivity for radiation in the visible spectrum = high emissivity for low temperature radiation = high convective heat transfer coefficient = low

Discussion

120.	Thermosetting plastics have in general:
A.	molecular chains that slip past one another when the material is heated sufficiently
B.	high strengths and low ductilities
C.	a covalently bonded 3-dimensional network or crosslinked structure
D.	both (A) and (C)
Answer» E.

Discussion

121.	Wood is a:
A.	granular material
B.	cellular material
C.	homogeneous material
D.	amorphous material
Answer» C. homogeneous material

Discussion

122.	An electrician s solder is generally an alloy of:
A.	iron and mercury
B.	zinc and copper
C.	copper and lead
D.	tin and lead
Answer» E.

Discussion

123.	The tunnel effect refers to:
A.	the migration of conducting electrons in a magnetic field
B.	the use of lasers in surveying
C.	the ability of electrons to exist on both sides of a large energy barrier
D.	the existence of cathode rays in a vacuum
Answer» D. the existence of cathode rays in a vacuum

Discussion

124.	A p-type germanium semiconductor is doped with:
A.	Selenium
B.	Gallium
C.	Arsenic
D.	Silicon
Answer» C. Arsenic

Discussion

125.	The decreasing order of the electrical resistivities of nichrome, silicon and diamond is:
A.	nichrome, silicon, diamond
B.	silicon, diamond, nichrome
C.	diamond, nichrome, silicon
D.	diamond, silicon, nichrome
Answer» E.

Discussion

126.	If the lattice temperature is increased, then the Hall coefficient of a semiconductor will:
A.	decrease
B.	increase
C.	first increase to peak and then decrease
D.	remain constant
Answer» D. remain constant

Discussion

127.	The Hall coefficient of an intrinsic semiconductor is:
A.	positive under all conditions
B.	negative under all conditions
C.	zero under all conditions
D.	zero at 0 K
Answer» C. zero under all conditions

Discussion

128.	The room temperature resistivity (in ohm-metre) of pure silicon is:
A.	3000
B.	300
C.	30
D.	3
Answer» B. 300

Discussion

129.	Some magnetic materials may be classified on the basis of:
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

130.	A type I superconductor maintained at a temperature T < T
A.	perfect diamagnetism
B.	partial diamagnetism
C.	perfect paramagnetism
D.	partial paramagnetism
Answer» B. partial diamagnetism

Discussion

131.	Consider the following metals:
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

132.	What type of magnetic behaviour is observed in a type-I superconductor?
A.	Perfect diamagnetism
B.	Perfect paramagnetism
C.	Perfect ferromagnetism
D.	Perfect ferrimagnetism
Answer» B. Perfect paramagnetism

Discussion

133.	Some of the characterising parameters of a materials are:
A.	1 and 3
B.	3 and 2
C.	4 and 3
D.	1 and 2
Answer» C. 4 and 3

Discussion

134.	The carbon percentage is least in:
A.	low carbon steel
B.	wrought iron
C.	cast iron
D.	malleable iron
Answer» B. wrought iron

Discussion

135.	Superconducting metal in a superconducting state has relative permeability of:
A.	zero
B.	one
C.	negative
D.	more than one
Answer» B. one

Discussion

136.	If the domain walls in a magnetic material can be easily moved, the material displays:
A.	permanent magnetic behaviour
B.	high flux density
C.	high permeability
D.	none of the above
Answer» D. none of the above

Discussion

137.	A paramagnetic material is used in an energy conversion process in which the following events occur:
A.	3, 4, 2, 1
B.	1, 4, 2, 3
C.	1, 2, 4, 3
D.	3, 2, 4, 1
Answer» E.

Discussion

138.	Which of the following pair(s) is/are correctly matched?
A.	only 2
B.	1 and 2
C.	1 and 3
D.	2 and 3
Answer» D. 2 and 3

Discussion

139.	The number of stress coefficients or constants which characterize a piezoelectric material is:
A.	24
B.	18
C.	9
D.	3
Answer» B. 18

Discussion

140.	A P-type semiconductor considered as a whole is:
A.	electrically neutral
B.	positively charged
C.	negatively charged
D.	None of these
Answer» B. positively charged

Discussion

141.	The highest mobility is associated with:
A.	holes
B.	electrons
C.	positive ion
D.	negative ion
Answer» E.

Discussion

142.	The Miller indices of the diagonal plane of a cube are:
A.	110
B.	111
C.	100
D.	000
Answer» B. 111

Discussion

143.	The crystal structure of most of the common metals is:
A.	hexagonal
B.	cubic
C.	orthorhombic
D.	None of these
Answer» C. orthorhombic

Discussion

144.	The nature of atomic bond found in diamond is:
A.	ionic
B.	covalent
C.	metallic
D.	None of these
Answer» C. metallic

Discussion

145.	The overall electrical neutrality is maintained in:
A.	Frenkel s defect
B.	screw dislocation
C.	low angle boundary defect
D.	none of the above
Answer» B. screw dislocation

Discussion

146.	Line imperfection in a crystal is called:
A.	Schottky defect
B.	Frenkel defect
C.	Edge dislocation
D.	Miller defect
Answer» D. Miller defect

Discussion

147.	Dislocations in materials are:
A.	point defect
B.	line defect
C.	planer defect
D.	surface defects
Answer» C. planer defect

Discussion

148.	Hall effect:
A.	describes the behaviour of minority carriers in a semiconductor under the influence of a magnetic field
B.	can be used to find whether a semiconductor is of Ntype or P-type
C.	cannot be used to determine the concentration of carriers and their mobility
D.	is a phenomenon applicable to semiconductors alone
Answer» C. cannot be used to determine the concentration of carriers and their mobility

Discussion

149.	Bakelite is a:
A.	acrylate
B.	silicon varnish
C.	thermoplastic synthetic resin
D.	phenol formaldehyde resin
Answer» E.

Discussion

150.	All of the following substances are hygroscopic EXCEPT:
A.	Silica gel
B.	Calcium chloride
C.	Sulphuric acid
D.	Sodium chloride
Answer» E.

Discussion

Explore topic-wise MCQs in Electrical Engineering materials.

Which of the following statements relate to the Hall effect?

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

The conductivity of a semiconductor crystal due to any current carrier is NOT proportional to:

Consider the following statements: In a transformer, the core material should have low

Gold, which has an atomic radius of 0.144 nm, crystallizes in a FCC structure. The lattice parameter of gold is:

When a semiconductor bar is heated at one end, a voltage across the bar is developed. If the heated end is positive, the semiconductor is:

When copper is added to silver in small quantity so as to form an alloy, the resistivity of such an alloy is:

When BCC iron is heated, it charges to FCC iron resulting in:

A fine powder of a refractory metal may be added to a molten metal prior to solidification of the metal. The fine powder may act to:

Hall effect device can be used to:

Electron mobility and life-time in a semiconductor at room temperature are respectively 0.36m

For which of the following semiconductors, resistance does not follow Ohm s law over some specific range of the applied voltage?

Consider the following statements: The dielectric constant of an insulator depends on

Ferromagnetics owe their properties to:

The temperature at or above which a ferromagnetic material becomes paramagnetic is called:

Which of the following statements are correct for ceramic materials?

For a medium carbon steel, having a 0.50% carbon content, slow cooling of austenite will cause austenite to transform to carbide and ferrite. Rapid quenching of austenite can result in:

The effect of temperature on the strength of linear thermoplastics is that:

In the selection of an opaque surface to act as collector of solar energy. It would be desirable for the surface to have which of the following sets of characteristics?

Thermosetting plastics have in general:

Wood is a:

An electrician s solder is generally an alloy of:

The tunnel effect refers to:

A p-type germanium semiconductor is doped with:

The decreasing order of the electrical resistivities of nichrome, silicon and diamond is:

If the lattice temperature is increased, then the Hall coefficient of a semiconductor will:

The Hall coefficient of an intrinsic semiconductor is:

The room temperature resistivity (in ohm-metre) of pure silicon is:

Some magnetic materials may be classified on the basis of:

A type I superconductor maintained at a temperature T < T

Consider the following metals:

What type of magnetic behaviour is observed in a type-I superconductor?

Some of the characterising parameters of a materials are:

The carbon percentage is least in:

Superconducting metal in a superconducting state has relative permeability of:

If the domain walls in a magnetic material can be easily moved, the material displays:

A paramagnetic material is used in an energy conversion process in which the following events occur:

Which of the following pair(s) is/are correctly matched?

The number of stress coefficients or constants which characterize a piezoelectric material is:

A P-type semiconductor considered as a whole is:

The highest mobility is associated with:

The Miller indices of the diagonal plane of a cube are:

The crystal structure of most of the common metals is:

The nature of atomic bond found in diamond is:

The overall electrical neutrality is maintained in:

Line imperfection in a crystal is called:

Dislocations in materials are:

Hall effect:

Bakelite is a:

All of the following substances are hygroscopic EXCEPT: