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EEE : Magnetism and Electromagnetism - Quiz(MCQ)
1 .
Strength of an electromagnet can be increased by
A)
increasing current supply
B)
increasing the number of turns
C)
increasing the cross-sectional area
D)
All of the above

Correct Answer :   All of the above

2 .
Which of the following is not a unit of flux?
A)
Telsa
B)
Weber
C)
Maxwell
D)
All of the above

Correct Answer :   Telsa

3 .
The magnetism left in the iron after exciting field has been removed is known as
A)
susceptance
B)
reluctance
C)
residual magnetism
D)
permeance

Correct Answer :   residual magnetism

4 .
The retentivity (a property) of material is useful for the construction of
A)
transformers
B)
permanent magnets
C)
electromagnets
D)
non-magnetic substances

Correct Answer :   permanent magnets

5 .
Materials subjected to rapid reversal of magnetism should have
A)
large area oiB-H loop
B)
high co-ercivity and low density
C)
high co-ercivity and high retentivity
D)
high permeability and low hysteresis loss

Correct Answer :   high permeability and low hysteresis loss

6 .
Hysteresis loop in case of magnetically hard materials is more in shape as compared to magnetically soft materials.
A)
circular
B)
triangular
C)
rectangular
D)
None of the above

Correct Answer :   rectangular

7 .
The relative permeability of materials is not constant.
A)
insulating
B)
diamagnetic
C)
paramagnetic
D)
ferromagnetic

Correct Answer :   ferromagnetic

8 .
Substances which have permeability less than the permeability of free space are known as
A)
Bipolar
B)
Diamagnetic
C)
Paramagnetic
D)
Ferromagnetic

Correct Answer :   Diamagnetic

9 .
A square cross-sectional magnet has a pole strength of 1 x 10 Wb and cross sectional area of 20 mm x 20 mm. What is the strength at a distance of 100 mm from the unit pole in air ?
A)
63.38 N/Wb
B)
633.8 N/Wb
C)
6338 N/Wb
D)
63380 N/Wb

Correct Answer :   6338 N/Wb

10 .
Paramagnetic materials have relative permeability
A)
slightly more than unity
B)
equal to unity
C)
slightly less than unity
D)
equal to that ferromagnetic mate rials

Correct Answer :   slightly more than unity

11 .
In a simple magnetic field the strength of magnet flux
A)
first increases and then decreases till it becomes zero
B)
increases continuously from initial value to final value
C)
decreases continuously from initial value to final value
D)
is constant and has same value in energy part of the magnetic field

Correct Answer :   first increases and then decreases till it becomes zero

12 .
The magnetic materials exhibit the property of magnetisation because of
A)
Spin of electrons
B)
Spin of nucleus
C)
Orbital motion of electrons
D)
None of the above

Correct Answer :   Spin of nucleus

13 .
A rectangular magnet of magnetic moment M is cut into two piece of same length, the magnetic moment of each piece will be
A)
M
B)
M/2
C)
2M
D)
M/4

Correct Answer :   M/2

14 .
Main causes of noisy solenoid are
A)
uneven bearing surface, caused by dirt or uneven wear between moving and stationary parts
B)
strong tendency of fan out of laminations at the end caused by repulsion among magnetic lines of force
C)
Both (A) and (B)
D)
None of the above

Correct Answer :   Both (A) and (B)

15 .
The most effective and quickest may of making a magnet from soft iron is by
A)
induction
B)
rubbing with another magnet
C)
the use of permanent magnet
D)
placing it inside a coil carrying current

Correct Answer :   placing it inside a coil carrying current

16 .
A 300 mm long conductor is carrying a current of 10 A and is situated at right angles to a magnetic field having a flux density of 0.8 T ; the force on the conductor will be
A)
0.24 N
B)
2.4 N
C)
24 N
D)
240 N

Correct Answer :   2.4 N

17 .
A material which is slightly repelled by a magnetic field is known as
A)
diamagnetic material
B)
conducting material
C)
paramagnetic material
D)
ferromagnetic material

Correct Answer :   diamagnetic material

18 .
The change of cross-sectional area of conductor in magnetic field will affect
A)
resistance of conductor
B)
reluctance of conductor
C)
(A) and (B) both in the same way
D)
None of the above

Correct Answer :   (A) and (B) both in the same way

19 .
The direction of magnetic lines of force is
A)
from south pole to north pole
B)
from north pole to south pole
C)
from one end of the magnet to another
D)
None of the above

Correct Answer :   from north pole to south pole

20 .
How does the magnetic compass needle behave in a magnetic field?
A)
It starts rotating
B)
It assures a position right angle to magnetic field
C)
It assures a position which follows a line of magnetic flux
D)
None of the above

Correct Answer :   It assures a position which follows a line of magnetic flux

21 .
A certain amount of current flows through a ring shaped coil with fixed number of turns. How does the magnetic induction B varies inside the coil if an iron core is threaded into coil without dimensional change of coil?
A)
Increases
B)
Decreases
C)
Remains same
D)
First increases and then decreases depending on the depth of iron in¬sertion

Correct Answer :   Increases

22 .
One telsa is equal to
A)
1 Wb/m
B)
1 Wb/m²
C)
1 mWb/m²
D)
1 Wb/mm²

Correct Answer :   1 Wb/m²

23 .
The susceptibility of paramagnetic materials generally lies between
A)
10⁻³ and 10⁻⁵
B)
10⁻² and 10⁻⁵
C)
10⁻³ and 10⁻⁷
D)
10⁻⁴ and 10⁻⁸

Correct Answer :   10⁻³ and 10⁻⁵

24 .
The materials are a bit inferior conductors of magnetic flux than air.
A)
dielectric
B)
diamagnetic
C)
paramagnetic
D)
ferromagnetic

Correct Answer :   diamagnetic

25 .
The ratio of intensity of magnetisation to the magnetisation force is known as
A)
flux density
B)
relative permeability
C)
susceptibility
D)
None of the above

Correct Answer :   susceptibility

26 .
What is the magnitude and the direction of force per 1.1m length of a pair of conductors of a direct current linecarrying 10 amperes and spaced 100 mm apart
A)
22 x 10⁻⁸ N
B)
22 x 10⁻⁷ N
C)
22 x 10⁻⁶ N
D)
22 x 10⁻⁵ N

Correct Answer :   22 x 10⁻⁵ N

27 .
The commonly used material for shielding or screening magnetism is
A)
brass
B)
soft iron
C)
copper
D)
aluminium

Correct Answer :   soft iron

28 .
Ferrites are materials.
A)
diamagnetic
B)
paramagnetic
C)
Both (A) and (B)
D)
ferromagnetic

Correct Answer :   ferromagnetic

29 .
The uniform magnetic field is
A)
the field of a single conductor
B)
the field of a set of parallel conductors
C)
the field in which all lines of magnetic flux are parallel and equidistant
D)
None of the above

Correct Answer :   the field in which all lines of magnetic flux are parallel and equidistant

30 .
Tesla is a unit of
A)
flux density
B)
flux
C)
inductance
D)
field strength

Correct Answer :   flux density

31 .
The bar magnet has
A)
monopole moment
B)
the dipole moment
C)
Both (A) and (B)
D)
None of the above

Correct Answer :   the dipole moment

32 .
The electromagnet has 50 turns and a current of 1A flows through the coil. If the length of the magnet circuit is 200 mm, what is the magnetic field strength?
A)
2.5 AT/m
B)
25 AT/m
C)
250 AT/m
D)
2500 AT/m

Correct Answer :   250 AT/m

33 .
If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity
A)
less than that of disc but in opposite direction
B)
less than that of disc and in the same direction
C)
equal to that of disc and in the same direction
D)
equal to that of disc and in the opposite direction

Correct Answer :   less than that of disc and in the same direction

34 .
The attraction capacity of electromagnet will increase if the
A)
flux density increases
B)
core area increases
C)
flux density decreases
D)
core length increases i

Correct Answer :   flux density increases

35 .
Which of the following is expected to have the maximum permeability?
A)
Zinc
B)
Brass
C)
Copper
D)
Ebonite

Correct Answer :   Ebonite

36 .
Which of the following is a vector quantity ?
A)
Flux density
B)
Magnetic potential
C)
Magnetic field intensity
D)
Relative permeability

Correct Answer :   Magnetic field intensity

37 .
What is the magneto-motive force (mmf) of a wire with 8 turns carrying three amperes of current?
A)
2.4 At
B)
24 At
C)
240 At
D)
2,400 At

Correct Answer :   24 At

38 .
Magnetism of a magnet can be destroyed by
A)
heating
B)
hammering
C)
by inductive action of another magnet
D)
by all above methods

Correct Answer :   by all above methods

39 .
What is the magneto-motive force in a 75-turn coil of wire when there are 4 A of current through it?
A)
18.75 At
B)
30 At
C)
187 At
D)
300 At

Correct Answer :   300 At

40 .
A magnetic field exists around
A)
moving charges
B)
aluminium
C)
iron
D)
copper

Correct Answer :   moving charges

41 .
What will be the magnetic potential difference across the air gap of 2 cm length in magnetic field of 200 AT/m?
A)
2 AT
B)
4 AT
C)
6 AT
D)
10 AT

Correct Answer :   4 AT

42 .
When an iron piece is placed in a magnetic field
A)
the iron piece will break
B)
the magnetic field will not be affected
C)
the magnetic lines of force will bend away from their usual paths in order to pass through the piece
D)
the magnetic lines of force will bend away from their usual paths in order to go away from the piece

Correct Answer :   the magnetic lines of force will bend away from their usual paths in order to pass through the piece

43 .
If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage
A)
Is zero
B)
Increases
C)
Decreases
D)
Will remain constant

Correct Answer :   Is zero

44 .
The unit of flux is the same as that of
A)
resistance
B)
reluctance
C)
permeance
D)
pole strength

Correct Answer :   pole strength

45 .
A keeper is used to
A)
amplify flux
B)
restore lost flux
C)
provide a closed path for flux
D)
change the direction of magnetic lines

Correct Answer :   provide a closed path for flux

46 .
The stray line of magnetic flux is defined as
A)
a line vertical to the flux lines
B)
the mean length of a ring shaped coil
C)
a line of magnetic flux in a non-uniform field
D)
a line of magnetic flux which does not follow the designed path

Correct Answer :   a line of magnetic flux which does not follow the designed path

47 .
When two ends of a circular uniform wire are joined to the terminals of a battery, the field at the center of the circle
A)
will be zero
B)
will be infinite
C)
will depend on the radius of the circle
D)
will depend on the amount of e.m.f. applied

Correct Answer :   will depend on the radius of the circle

48 .
For which of the following materials the net magnetic moment should be zero?
A)
Diamagnetic materials
B)
Antiferromagnetic materials
C)
Ferrimagnetic materials
D)
Antiferrimagnetic materials

Correct Answer :   Antiferromagnetic materials

49 .
For a given wire-wound core, an increase in current through the coil
A)
Reverses the flux lines
B)
Increases the flux density
C)
Decreases the flux density
D)
Causes no change in flux density

Correct Answer :   Increases the flux density

50 .
Gilbert is a unit of
A)
permittivity
B)
conductance
C)
electromotive force
D)
magnetomotive force

Correct Answer :   magnetomotive force

51 .
Which of the following is the unit of magnetic flux density?
A)
Tesla
B)
Weber
C)
Lumens
D)
None of the above

Correct Answer :   Tesla

52 .
Indicate which of the following material does not retain magnetism permanently.
A)
Soft iron
B)
Stainless steel
C)
Hardened steel
D)
None of the above

Correct Answer :   Soft iron

53 .
The magnetomotive force is
A)
the flow of an electric current
B)
the voltage across the two ends of exciting coil
C)
the passage of magnetic field through an exciting coil
D)
the sum of all currents embraced by one line of magnetic field

Correct Answer :   the sum of all currents embraced by one line of magnetic field

54 .
Reciprocal of permeability is
A)
permittivity
B)
reluctivity
C)
conductance
D)
susceptibility

Correct Answer :   reluctivity

55 .
Susceptibility is positive for
A)
diamagnetic substances
B)
non-magnetic substances
C)
ferromagnetic substances
D)
None of the above

Correct Answer :   ferromagnetic substances

56 .
Which of the following materials are diamagnetic?
A)
Silver
B)
Copper
C)
Silver and Copper
D)
Iron

Correct Answer :   Silver and Copper

57 .
Magnetising steel is normals difficult because
A)
it corrodes easily
B)
it has low permeability
C)
it has high permeability
D)
it has high specific gravity

Correct Answer :   it has low permeability

58 .
For which of the following materials the saturation value is the highest?
A)
Ferrites
B)
Diamagnetic materials
C)
Paramagnetic materials
D)
Ferromagnetic materials

Correct Answer :   Ferrites

59 .
Magnetic moment is a
A)
scalar quantity
B)
pole strength
C)
universal constant
D)
vector quantity

Correct Answer :   vector quantity

60 .
The use of permanent magnets is. not made in
A)
magnetoes
B)
transformers
C)
energy meters
D)
loud-speakers

Correct Answer :   transformers

61 .
Degaussing is the process of
A)
demagnetising metallic parts
B)
remagnetising metallic parts
C)
removal of magnetic impurities
D)
removing gases from the materials

Correct Answer :   demagnetising metallic parts

62 .
Air gap has_______eluctance as compared to iron or steel path
A)
zero
B)
little
C)
lower
D)
higher

Correct Answer :   lower

63 .
Core of an electromagnet should have
A)
low coercivity
B)
high susceptibility
C)
Both (A) and (B)
D)
None of the above

Correct Answer :   Both (A) and (B)

64 .
Ferrites are a sub-group of
A)
non-magnetic materials
B)
paramagnetic materials
C)
ferro-magnetic materials
D)
ferri-magnetic materials

Correct Answer :   ferri-magnetic materials

65 .
Out of the following statements, concerning an electric field, which statement is not true?
A)
The electric intensity is a vector quantity
B)
The electric field intensity at a point is numerically equal to the force exerted upon a charge placed at that point
C)
Unit field intensity in the exertion of a force of one newton on a charge of one coulomb
D)
An electric field is defined as a point in space at which an electric charge would experience a force

Correct Answer :   The electric field intensity at a point is numerically equal to the force exerted upon a charge placed at that point

66 .
The unit of relative permeability is
A)
henry
B)
henry/sq. m
C)
henry/metre
D)
it is dimensionless

Correct Answer :   it is dimensionless

67 .
A 200 turn coil having an axial length of 30 mm and a radius of 10 mm is pivoted in a magnetic field having a flux density of 0.8 T. If the coil carries a current of 0.5 A, the torque acting on the coil will be
[Hint. Torque = 2BIlNr N-m]
A)
8 N-m
B)
0.48 N-m
C)
0.048 N-m
D)
0.0048 N-m

Correct Answer :   0.048 N-m

68 .
The working of a meter is based on the use of a permanent magnet. In order to protect the meter functioning from stray magnetic fields
A)
a soft iron shielding is used
B)
a plastic shielding is provided
C)
a shielding of anon-magnetic material is used
D)
meter is surrounded by strong magnetic fields

Correct Answer :   a soft iron shielding is used

69 .
The initial permeability of an iron rod is
A)
the lowest permeability of the iron rod
B)
the highest permeability of the iron rod
C)
the permeability almost in non-magnetised state
D)
the permeability at the end of the iron rod

Correct Answer :   the permeability almost in non-magnetised state

70 .
Unit for quantity of electricity is
A)
watt
B)
joule
C)
coulomb
D)
ampere-hour

Correct Answer :   coulomb

71 .
The main constituent of permalloy is
A)
cobalt
B)
nickel
C)
tungsten
D)
chromium

Correct Answer :   nickel

72 .
Temporary magnets are used in
A)
motors
B)
generators
C)
loud-speakers
D)
All of the above

Correct Answer :   All of the above

73 .
One maxwell is equal to
A)
10⁴ webers
B)
10⁻⁴ webers
C)
10⁸ webers
D)
10⁻⁸ webers

Correct Answer :   10⁴ webers

74 .
A permanent magnet________
A)
attracts only ferromagnetic substances
B)
attracts some substances and repels others
C)
attracts all paramagnetic substances and repels others
D)
attracts ferromagnetic substances and repels all others

Correct Answer :   attracts some substances and repels others

75 .
Two infinitely long parallel conductors in vacuum any separated 1 metre between centers >then a current of 1 ampere flows the. uk each conductor, produce on each other a force of
A)
2 x 1(T2 N/m)
B)
2 x KT3 N/m
C)
2 x 10"5 N/m
D)
2x 1(T7 N/m)

Correct Answer :   2x 1(T7 N/m)

76 .
A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will
A)
Increase
B)
Decrease
C)
Be excessive
D)
Remain constant

Correct Answer :   Decrease

77 .
Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per meter of length of each conductor will be
A)
0.1 N
B)
1 N
C)
10 N
D)
100 N

Correct Answer :   0.1 N

78 .
The magnetic reluctance of a material
A)
decreases with increasing cross sectional area of material
B)
increases with increasing cross-sec-tional area of material
C)
does not vary with increasing cross-sectional area of material
D)
Any of the bove

Correct Answer :   decreases with increasing cross sectional area of material

79 .
The left hand rule correlates to
A)
current, induced e.m.f. and direction of force on a conductor
B)
magnetic field, electric field and direction of force on a conductor
C)
current, magnetic field and direction of force on a conductor
D)
self induction, mutual induction and direction of force on a conductor

Correct Answer :   current, magnetic field and direction of force on a conductor

80 .
When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon
A)
Resistance of the coil
B)
Motion of the magnet
C)
Number of turns of the coil
D)
Pole strength of the magnet

Correct Answer :   Resistance of the coil

81 .
In the left hand rule, forefinger always represents
A)
voltage
B)
current
C)
magnetic field
D)
direction of force on the conductor

Correct Answer :   magnetic field

82 .
The Biotsavart's law is a general modification of
A)
Lenz's law
B)
Ampere's law
C)
Kirchhoff's law
D)
Faraday's laws

Correct Answer :   Ampere's law

83 .
What will be the current passing through the ring shaped air cored coil when number of turns is 800 and ampere turns are 3200?
A)
2
B)
4
C)
6
D)
8

Correct Answer :   4

84 .
Which of the following type of materials are not very important for engineering applications?
A)
Diamagnetic
B)
Paramagnetic
C)
Ferromagnetic
D)
None of the above

Correct Answer :   Diamagnetic

85 .
The relative permeability is less than unity is case of
A)
ferrites
B)
non-ferrous materials
C)
ferromagnetic materials
D)
diamagnetic materials

Correct Answer :   diamagnetic materials

86 .
A conductor of length L has current I passing through it, when it is placed parallel to a magnetic field. The force experienced by the conductor will be
A)
Zero
B)
BLI
C)
B2LI
D)
BLI2

Correct Answer :   Zero

87 .
Which of the following is a ferromagnetic material?
A)
Copper
B)
Nickel
C)
Tungsten
D)
Aluminium

Correct Answer :   Nickel

88 .
The two conductors of a transmission line carry equal current I in opposite directions. The force on each conductor is
A)
proportional to X
B)
proportional to 7
C)
inversely proportional to I
D)
proportional to distance between the conductors

Correct Answer :   proportional to X