9294 + Mcqs in Electronics and Communication Engineering Page 149 McqOptions

7401.	A vacant electronic state moves in the same direction as would a positive charge carrier.
A.	True
B.	False
Answer» B. False

Discussion

7402.	Piezoelectricity means the slight change in dimensions of a specimen when an electric field is applied.
A.	True
B.	False
Answer» B. False

Discussion

7403.	Many compounds also exhibit semiconducting properties.
A.	True
B.	False
Answer» B. False

Discussion

7404.	On the basis of the type of chemical bonds, solids may be classified into
A.	ionic crystals
B.	ionic and valence crystals
C.	ionic crystal, valence crystals and metals
D.	ionic crystals, valence crystals, metal and vander wall crystals
Answer» E.

Discussion

7405.	The units for intrinsic strength of dielectric are
A.	kV
B.	kV/m
C.	A
D.	A/m
Answer» C. A

Discussion

7406.	Assertion (A): If an electron having charge e is revolving in an orbit of radius R and with angular velocity , the magnetic dipole moment of orbit is 0.5 e R2.Reason (R): Orbital angular momentum and magnetic dipole moment are always equal.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» D. A is false but R is true

Discussion

7407.	The v-i relation for an arc is v = 44 + . If v = 50 V, i =
A.	10 A
B.	5 A
C.	2 A
D.	0.5 A
Answer» C. 2 A

Discussion

7408.	Which inductor is linear?
A.	Air cored
B.	Cast iron cored
C.	Sheet steel cored
D.	Iron alloy cored
Answer» B. Cast iron cored

Discussion

7409.	Which inductor is used at high frequencies?
A.	Cast iron cored
B.	Sheet steel cored
C.	Iron alloy cored
D.	Ceramic cored
Answer» E.

Discussion

7410.	Magnetisation of a material is the magnetic dipole moment per m3.
A.	True
B.	False
Answer» B. False

Discussion

7411.	Debye temperature of metals is
A.	about 10 K
B.	about 200 K
C.	about 600 K
D.	about 2 K
Answer» C. about 600 K

Discussion

7412.	As the viscosity of a liquid increases, the relaxation time
A.	remains constant
B.	increases
C.	decreases
D.	first decreases then increases
Answer» C. decreases

Discussion

7413.	A wire is carrying current I. The field intensity H at a distance r from the wire
A.	is directed towards wire
B.	is directed away from wire
C.	is tangential every where to a circle of radius
D.	<i>r</i>
E.	none of the above
Answer» D. <i>r</i>

Discussion

7414.	The materials which become polarized on the application of mechanical stress are called piezoelectric.
A.	True
B.	False
Answer» B. False

Discussion

7415.	Assertion (A): A capacitor with imperfect dielectric can be represented by a capacitance in parallel with resistance.Reason (R): For imperfect dielectrics, dielectric constant has real and imaginary parts.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» B. Both A and R are true but R is not correct explanation of A

Discussion

7416.	An atom of a rare gas is placed is an electric field E. Then
A.	the nucleus will be shifted in the direction of E by an amount which is proportional to E.
B.	the nucleus will not be shifted.
C.	the nucleus will be shifted in the direction of E by an amount which is independent of E.
D.	the nucleus will be shifted in a direction opposite to that of E.
Answer» B. the nucleus will not be shifted.

Discussion

7417.	In van der walls crystals, there exists a high degree of stability of the outer electron shell.
A.	True
B.	False
Answer» B. False

Discussion

7418.	A characteristic property of crystal is its periodicity of structure.
A.	True
B.	False
Answer» B. False

Discussion

7419.	If m is the mass of electron cloud, the equation of motion of electron cloud in the presence of an alternating electric field is of the form
A.	<img src="/_files/images/electronics-and-communication-engineering/materials-and-components/64-1.png">
B.	<img src="/_files/images/electronics-and-communication-engineering/materials-and-components/64-2.png">
C.	<img src="/_files/images/electronics-and-communication-engineering/materials-and-components/64-3.png">
D.	<img src="/_files/images/electronics-and-communication-engineering/materials-and-components/64-4.png">
Answer» B. <img src="/_files/images/electronics-and-communication-engineering/materials-and-components/64-2.png">

Discussion

7420.	The rule that resistivity of conductors can be separated into two parts viz. temperature independent and temperature dependent is known as
A.	Matthiessen's rule
B.	Debye rule
C.	Curie rule
D.	Onne's rule
Answer» B. Debye rule

Discussion

7421.	Assertion (A): Electron concentration n, hole concentration p and charge concentration ni are related by ni2 = np.Reason (R): p type semiconductor is obtained by adding trivalent impurity to intrinsic semiconductor.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» C. A is true but R is false

Discussion

7422.	For making a capacitor it is better to have a dielectric having
A.	high permittivity
B.	low permittivity
C.	permittivity same as that of air
D.	permittivity which is neither high nor low
Answer» B. low permittivity

Discussion

7423.	Assertion (A): The regular or irregular stacking of atoms has importanteffect on properties of materials.Reason (R): The arrangement of atoms in a given material can be studied using X-rays.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» C. A is true but R is false

Discussion

7424.	If temperature is increased, the temperature coefficient of a metal
A.	increases
B.	decreases
C.	may increase or decrease
D.	remains constant
Answer» C. may increase or decrease

Discussion

7425.	In a valence crystal, the valence electrons
A.	are not shared
B.	are shared between neighbouring atoms
C.	are shared by all atoms
D.	any of the above
Answer» C. are shared by all atoms

Discussion

7426.	Transformer oil is
A.	refined vegetable oil
B.	refined mineral oil
C.	mixture of vegetable and mineral oil
D.	none of the above
Answer» C. mixture of vegetable and mineral oil

Discussion

7427.	A dielectric material must be
A.	insulator
B.	good conductor
C.	resistor
D.	semiconductor
Answer» B. good conductor

Discussion

7428.	Assertion (A): Drift velocity of electrons is proportional to the applied electric field E.Reason (R): The average drift velocity per unit field is called mobility.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» C. A is true but R is false

Discussion

7429.	The materials having low retentivity are suitable for making
A.	temporary smagnets
B.	weak magnets
C.	permanent magnets
D.	both temporary and permanent magnets
Answer» B. weak magnets

Discussion

7430.	Above a certain temperature, the specific heat of a metal becomes constant. This temperature is called
A.	Debye temperature
B.	Curie temperature
C.	Neel temperature
D.	Transition temperature
Answer» B. Curie temperature

Discussion

7431.	Spontaneous magnetisation is characteristic of ferromagnetic materials.
A.	True
B.	False
Answer» B. False

Discussion

7432.	The application of magnetic field to superconducting material
A.	increases transition temperature
B.	decreases transition temperature
C.	has no effect on transition temperature
D.	may increase or decrease the transition temperature
Answer» C. has no effect on transition temperature

Discussion

7433.	Automobile ignition systems use the principle of
A.	resistance
B.	self inductance
C.	mutual inductance
D.	capacitance
Answer» D. capacitance

Discussion

7434.	Resistivity of copper is lower than that of nickel. When a small percentage of copper is added to nickel, the resistivity
A.	increases
B.	decreases
C.	may increase or decrease
D.	remains the same
Answer» B. decreases

Discussion

7435.	If r = r' - j r" tan = .
A.	True
B.	False
Answer» B. False

Discussion

7436.	If 0 is the angular frequency of rotation of electron in the absence of magnetic field, the angular frequency , when a magnetic field B is acting is 0 + (e/2m)B.
A.	True
B.	False
Answer» B. False

Discussion

7437.	The resistance of a superconductor is
A.	low
B.	very low
C.	very very low
D.	zero
Answer» E.

Discussion

7438.	The amount of time between the creation and recombination of a free electron and hole is called
A.	relaxation time
B.	life time
C.	lorentz time
D.	collision time
Answer» C. lorentz time

Discussion

7439.	Dielectric constant, under the condition of alternating fields, is a complex quantity.
A.	True
B.	False
Answer» B. False

Discussion

7440.	For a superconductor, magnetisation M in a field H is
A.	extremely small
B.	- H
C.	- I
D.	zero
Answer» C. - I

Discussion

7441.	When temperature is more than ferromagnetic curie temperature, the behaviour of a ferromagnetic material is similar to that of paramagnetic material.
A.	True
B.	False
Answer» B. False

Discussion

7442.	A photoconductor is a
A.	conductor
B.	semiconductor
C.	insulator
D.	superconductor
Answer» C. insulator

Discussion

7443.	Assertion (A): Both sodium and ferrous are ferromagnetic.Reason (R): Both sodium and ferrous have body centred cubic structure.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» C. A is true but R is false

Discussion

7444.	Lines of magnetic field attract each other.
A.	True
B.	False
Answer» C.

Discussion

7445.	For iron, the ferromagnetic Curie temperature is
A.	about 20 K
B.	about 100 C
C.	about -20 C
D.	about 1000 K
Answer» E.

Discussion

7446.	The number of valence electrons in germanium atom is
A.	4
B.	2
C.	1
D.	zero
Answer» B. 2

Discussion

7447.	Assertion (A): 0 has the dimensions of farad per meter.Reason (R): D = 0 r E.
A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not correct explanation of A
C.	A is true but R is false
D.	A is false but R is true
Answer» C. A is true but R is false

Discussion

7448.	As regards dielectric constant r
A.	the units are farads/m
B.	the units are newton/coulomb
C.	it is dimensionless
D.	the units are farads
Answer» D. the units are farads

Discussion

7449.	The maximum temperature limit of class B insulation is
A.	90 C
B.	105 C
C.	120 C
D.	130 C
Answer» E.

Discussion

7450.	In ferromagnetic materials, the orientation between neighbouring permanent dipoles is parallel.
A.	True
B.	False
Answer» B. False

Discussion

Explore topic-wise MCQs in Engineering.

A vacant electronic state moves in the same direction as would a positive charge carrier.

Piezoelectricity means the slight change in dimensions of a specimen when an electric field is applied.

Many compounds also exhibit semiconducting properties.

On the basis of the type of chemical bonds, solids may be classified into

The units for intrinsic strength of dielectric are

Assertion (A): If an electron having charge e is revolving in an orbit of radius R and with angular velocity , the magnetic dipole moment of orbit is 0.5 e R2.Reason (R): Orbital angular momentum and magnetic dipole moment are always equal.

The v-i relation for an arc is v = 44 + . If v = 50 V, i =

Which inductor is linear?

Which inductor is used at high frequencies?

Magnetisation of a material is the magnetic dipole moment per m3.

Debye temperature of metals is

As the viscosity of a liquid increases, the relaxation time

A wire is carrying current I. The field intensity H at a distance r from the wire

The materials which become polarized on the application of mechanical stress are called piezoelectric.

Assertion (A): A capacitor with imperfect dielectric can be represented by a capacitance in parallel with resistance.Reason (R): For imperfect dielectrics, dielectric constant has real and imaginary parts.

An atom of a rare gas is placed is an electric field E. Then

In van der walls crystals, there exists a high degree of stability of the outer electron shell.

A characteristic property of crystal is its periodicity of structure.

If m is the mass of electron cloud, the equation of motion of electron cloud in the presence of an alternating electric field is of the form

The rule that resistivity of conductors can be separated into two parts viz. temperature independent and temperature dependent is known as

Assertion (A): Electron concentration n, hole concentration p and charge concentration ni are related by ni2 = np.Reason (R): p type semiconductor is obtained by adding trivalent impurity to intrinsic semiconductor.

For making a capacitor it is better to have a dielectric having

Assertion (A): The regular or irregular stacking of atoms has importanteffect on properties of materials.Reason (R): The arrangement of atoms in a given material can be studied using X-rays.

If temperature is increased, the temperature coefficient of a metal

In a valence crystal, the valence electrons

Transformer oil is

A dielectric material must be

Assertion (A): Drift velocity of electrons is proportional to the applied electric field E.Reason (R): The average drift velocity per unit field is called mobility.

The materials having low retentivity are suitable for making

Above a certain temperature, the specific heat of a metal becomes constant. This temperature is called

Spontaneous magnetisation is characteristic of ferromagnetic materials.

The application of magnetic field to superconducting material

Automobile ignition systems use the principle of

Resistivity of copper is lower than that of nickel. When a small percentage of copper is added to nickel, the resistivity

If r = r' - j r" tan = .

If 0 is the angular frequency of rotation of electron in the absence of magnetic field, the angular frequency , when a magnetic field B is acting is 0 + (e/2m)B.

The resistance of a superconductor is

The amount of time between the creation and recombination of a free electron and hole is called

Dielectric constant, under the condition of alternating fields, is a complex quantity.

For a superconductor, magnetisation M in a field H is

When temperature is more than ferromagnetic curie temperature, the behaviour of a ferromagnetic material is similar to that of paramagnetic material.

A photoconductor is a

Assertion (A): Both sodium and ferrous are ferromagnetic.Reason (R): Both sodium and ferrous have body centred cubic structure.

Lines of magnetic field attract each other.

For iron, the ferromagnetic Curie temperature is

The number of valence electrons in germanium atom is

Assertion (A): 0 has the dimensions of farad per meter.Reason (R): D = 0 r E.

As regards dielectric constant r

The maximum temperature limit of class B insulation is

In ferromagnetic materials, the orientation between neighbouring permanent dipoles is parallel.