3. What will happen to an insulating medium if voltage more than the breakdown
voltage is applied on it ?
Correct : C. It will get punctured or cracked
4. Which medium has the least dielectric strength ?
Correct : D. Air
5. 1 volt/metre is same as
Correct : C. 1 newton/metre
6. One volt is the same as
Correct : A. one joule/coulomb
7. The capacitance between two plates increases with
Correct : D. larger plate area and shorter distance between plates
8. The capacitance C is charged through a resistance R. The time constant of the charging
circuit is given by
Correct : C. RC
9. The bridge used for the measurement of the value of the capacitance is
Correct : C. Schering bridge
10. If an ohmmeter reading immediately goes practically to zero and stays there, capacitor
is
Correct : B. short-circuited
11. Out of the following capacitors of identical rating which one will have the smallest
dimensions ?
Correct : C. Ceramic capacitor
12. An uncharged conductor is placed near a charged conductor, then
Correct : B. the uncharged conductor gets charged by induction and then attracted towards the charging body
13. The presence of an uncharged conductor near a charged one increases the
Correct : B. capacity of the charged conductor
14. Paper condenser is
Correct : B. usually of fixed value
15. Mica capacitors are characterised by all of thte following except
Correct : C. low leakage reactance
16. A potential of 400 V is applied to a capacitor, the plates of which are 4 mm apart. The
strength of electric field is
Correct : A. 100 kV/m
17. For a good 0.05 uF capacitor ohmmeter reading should
Correct : A. show low resistance momentarily and back off to a very high resis¬tance
18. The ohmmeter reading for a short circuited capacitor is
Correct : D. zero
19. Which of the following statements is correct ?
Correct : C. Electrolytic capacitors must be connected in correct polarity
20. Which of the following capacitors preferred for high frequency circuits ?
Correct : C. Mica capacitor
21. An electrolytic capacitor is generally made to provide
Correct : D. large value of capacitance
22. In order to remove static electricity from machinery
Correct : C. ground the framework
23. If a third equal and similar charge is placed between two equal and similar charges,
then this third charge will
Correct : B. remain in stable equilibrium
24. A region around a stationary electric charge has
Correct : A. an electric field
25. The minimum value of potential gradient in a cable occurs in
Correct : A. insulation
26. Dielectric strength of medium
Correct : D. none of the above
27. Acharge which when placed in vacuum from an equal and similar charge repels with a
force of 9 x 10 N, is known as
Correct : B. micro-coulomb
28. Dielectric strength of a medium is usually expressed in
Correct : C. kV/mm
29. A positive and a negative charge are initially 50 mm apart. When they are moved close
together so that they are now only 10 mm apart, the force between them will be
Correct : D. 25 times larger than before
30. Which is the most superior dielectric out of the following ?
Correct : C. Bakelite
31. When a dielectric is placed in an electric field the field strength
Correct : A. decreases
32. To prevent the generation of static charges on rubber or flat leather
Correct : B. conductive dressing is done
33. Which of the following capacitor is preferred in case of single phase motor ?
Correct : C. Electrolytic capacitor
34. A capacitance is a circuit component that opposes the change in circuit
Correct : B. voltage
35. A condenser suitable for D.C. only is
Correct : D. poled aluminium electrolytic condenser
36. In a capacitor, the electric charge is stored in
Correct : B. dielectric
37. Tesla is a unit of
Correct : C. flux density
38. A permeable substance is one
Correct : D. through which the magnetic lines of force can pass very easily
39. The materials having low retentivity are suitable for making
Correct : B. temporary magnets
40. A magnetic field exists around
Correct : D. moving charges
41. Ferrites are materials.
Correct : C. ferromagnetic
42. Air gap has_______eluctance as compared to iron or steel path
Correct : B. lower
43. The direction of magnetic lines of force is
Correct : B. from north pole to south pole
44. Which of the following is a vector quantity ?
Correct : B. Magnetic field intensity
45. The two conductors of a transmission line carry equal current I in opposite directions.
The force on each conductor is
Correct : B. proportional to X
46. A material which is slightly repelled by a magnetic field is known as
Correct : B. diamagnetic material
47. When an iron piece is placed in a magnetic field
Correct : B. the magnetic lines of force will bend away from their usual paths in order to pass through the piece
48. Fleming's left hand rule is used to find
Correct : C. direction of force on a current car¬rying conductor in a magnetic field
49. The ratio of intensity of magnetisation to the magnetisation force is known as
Correct : B. susceptibility
50. Magnetising steel is normals difficult because
Correct : D. it has low permeability
51. The left hand rule correlates to
Correct : D. current, magnetic field and direc¬tion of force on a conductor
52. The unit of relative permeability is
Correct : D. it is dimensionless
53. 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
Correct : A. zero
54. The force between two long parallel conductors is inversely proportional to
Correct : D. distance between the conductors
55. Materials subjected to rapid reversal of magnetism should have
Correct : B. high permeability and low hysteresis loss
56. Indicate which of the following material does not retain magnetism permanently.
Correct : A. Soft iron
57. The main constituent of permalloy is
Correct : C. nickel
58. The use of permanent magnets is. not made in
Correct : C. transformers
59. Paramagnetic materials have relative permeability
Correct : C. slightly more than unity
60. Substances which have permeability less than the permeability of free space are known
as
Correct : C. diamagnetic
61. Two infinitely long parallel conductors in vacuum anf' separated 1 metre between centres >rhen a current of 1 ampere flows thn. ugh each conductor, produce on each otLer a force of
Correct : D. 2x 1(T7 N/m)
62. In the left hand rule, forefinger always represents
Correct : C. magnetic field
63. Which of the following is a ferromagnetic material ?
Correct : D. Nickel
64. Ferrites are a sub-group of
Correct : D. ferri-magnetic materials
65. Gilbert is a unit of
Correct : B. magnetomotive force
66. 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
Correct : B. a soft iron shielding is used
67. Reciprocal of permeability is
Correct : A. reluctivity
68. The relative permeability is less than unity is case of
Correct : D. diamagnetic materials
69. Which of the following is the unit of magnetic flux density ?
Correct : C. tesla
70. The magnetism left in the iron after exciting field has been removed is known as
Correct : B. residual magnetism
71. Which of the following is not a unit of flux?
Correct : B. Telsa
72. Which of the following is expected to have the maximum permeability ?
Correct : D. Ebonite
73. One telsa is equal to
Correct : C. 1 Wb/m2
74. Out of the following statements, concerning an electric field, which statement is not true ?
Correct : B. The electric field intensity at a point is numerically equal to the force exerted upon a charge placed at that point
75. When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon
Correct : A. resistance of the coil
76. One maxwell is equal to
Correct : D. 10 webers
77. When two ends of a circular uniform wire are joined to the terminals of a battery, the
field at the centre of the circle
Correct : D. will depend on the radius of the circle
78. Susceptibility is positive for
Correct : C. ferromagnetic substances
79. Two long parallel conductors carry 100 A. If the conductors are separated by 20 mm, the force per metre of length of each conductor will be
Correct : D. 0.1 N
80. 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
Correct : C. 2.4 N
81. 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 ?
Correct : B. 250 AT/m
82. 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 ?
Correct : D. 22 x 10"5 N
83. 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 ?
Correct : C. 6338 N/Wb
84. The unit of flux is the same as that of
Correct : D. pole strength
85. Unit for quantity of electricity is
Correct : D. coulomb
86. The Biot-savart's law is a general modification of
Correct : C. Ampere's law
87. The most effective and quickest may of making a magnet from soft iron is by
Correct : A. placing it inside a coil carrying current
88. The commonly used material for shielding or screening magnetism is
Correct : C. soft iron
89. If a copper disc is rotated rapidly below a freely suspended magnetic needle, the
magnetic needle shall start rotating with a velocity
Correct : D. less than that of disc and in the same direction
90. A permanent magnet
Correct : A. attracts some substances and repels others
91. The retentivity (a property) of material is useful for the construction of
Correct : A. permanent magnets
92. The relative permeability of materials is not constant.
Correct : C. ferromagnetic
93. The materials are a bit inferior conductors of magnetic flux than air.
Correct : C. diamagnetic
94. Hysteresis loop in case of magnetically hard materials is more in shape as compared to
magnetically soft materials.
Correct : C. rectangular
95. A rectangular magnet of magnetic moment M is cut into two piece of same length, the
magnetic moment of each piece will be
Correct : B. M/2
96. A keeper is used to
Correct : D. provide a closed path for flux
97. Magnetic moment is a
Correct : D. vector quantity
98. The change of cross-sectional area of conductor in magnetic field will affect
Correct : C. (a) and (b) b >th in the same way
99. The uniform magnetic field is
Correct : C. the field in which all lines of mag¬netic flux are parallel and equidis¬tant
100. The magneto-motive force is
Correct : C. the sum of all currents embraced by one line of magnetic field