electrostatics Mcqs
51. Equipotential planes are_______________?
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A. parallel to one another

B. intersecting

C. circular

D. non parallel to one another

52. If the sheet of a bakelite is inserted between the plates of an air capacitor, the capacitance will__________?
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A. remains unchanged

B. become zero

C. increase

D. decrease

53. Value of ?r for various dielectrics is always________________?
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A. Less than unity

B. Larger than unit

C. Equal to the unit

D. No hard and fast rule

54. Which of the following statements is correct ___________?
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A. Mica capacitors are available in capacitance value of 1 to 10 pF

B. Ceramic capacitors must be connected in the correct polarity

C. Air capacitors have a black band to indicate the outside foil

D. Electrolytic capacitor must be connected in the correct polarity
55. A hollow metallic sphere of 8cm diameter is charged with 4 x 10 8C. The potential on its surface will be_________________?
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A. zero

B. 9000 volts

C. 90 volts

D. 900 volts

56. Electric flux due to a point charge +q is______________?
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A. 1/4II?0. q/r2

B. 1/4II? q/r

C. 4II?0

D. q/?0
57. When 4 volts e.m.f. is applied across a 1 farad capacitor, it will store energy of_____________?
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A. 2 joules

B. 8 joules

C. 4 joules

D. 6 joules

58. To prevent the generation of static charges on rubber or flat leather__________?
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A. oil compound dressing is done

B. conductive dressing is done

C. surface is moistened

D. talcum powder is sprayed on the surface

59. Which of the following materials has the highest value of dielectric constant___________?
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A. Vacuum

B. Oil

C. Glass

D. Ceramics

60. Which of the following capacitors preferred for high frequency circuits ?
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A. Mica capacitor

B. Air capacitor

C. none of the above

D. Electrolytic capacitor

61. N/C =_____________?
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A. V/A

B. J/V

C. V/m

D. A/m

62. Two infinite parallel plates 10 mm apart have maintained between them a potential difference of 100 V. The acceleration of an electron placed between them is______________?
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A. 0.56 x 1015 m/s2

B. 1.6 x 1015 m/s2

C. 1.76 x 1015 m/s2

D. 1.5 x 1015 m/s2

63. The units of capacitance are____________?
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A. henry/Wb

B. volts/coulomb

C. coulombs/volt

D. ohms

64. A capacitor stores 0.24 coulombs at 10 volts. Its capacitance is___________?
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A. 0.6 F

B. 0.12 F

C. 0.8 F

D. 0.024 F
65. When a dielectric slab is introduced in a parallel plate capacitor, the potential difference between plates will______________?
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A. become zero

B. decrease

C. increase

D. remain uncharged

66. If free space between the plates of a capacitor is replaced by a dielectric_____________?
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A. The potential difference remains constant capacittance and energy stored increases

B. The potential difference remains constant capacittance decreases and energy increases

C. The potential difference decreases but both capacitance and energy increase

D. both potential difference and capacitance decrease but energy increases

67. The property of a capacitor to store electricity is called its____________?
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A. none of the above

B. energy

C. charge

D. capacitance
68. For which of the following parameter variation, the capacitance of the capacitor remains unaffected ____________?
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A. Thickness of the plates

B. Nature of dielectric

C. Area of the plates

D. Distance between plates

69. Which of the following is not a vector ___________?
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A. Electric potential

B. Linear momentum

C. Electric field

D. Angular momentum
70. Electric displacement is a__________quantity
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A. scalar

B. vector

C. both of the above

D. none of the above

71. The sparking between two electrical contacts can be reduced by inserting a___________?
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A. none of the above

B. resistance in line

C. capacitor in series with each contact

D. capacitor in parallel with contacts
72. The capacitance of a capacitor is not affected by____________?
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A. thickness of plates

B. all of the above

C. distance between plates

D. area of plates

73. The time constant and R-C circuit may also be defined as the time during which the charging current falls to ________ percent of its initial maximum value
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A. 73

B. 37

C. 42

D. 63

74. If A.C. voltage is applied to capacitive circuit, the alternating current can flow in the circuit because__________________?
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A. varying voltage produces the charging and dicharging currents

B. of high peak value

C. charging current can flow

D. discharge current can flow

75. The dissipation factor of a good dielectric is of the order of____________?
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A. 0.2

B. 0.0002

C. 0.002

D. 0.02

76. A single core cable used on 33000 V has conductor diameter 10 mm and the internal diameter of sheath 25 mm. The maximum electrostatic stress in the cable is____________?
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A. 92 x 105 V/m

B. 82 x 105 V/m

C. 72 x 105 V/m

D. 62 x 105 V/m

77. A region around a stationary electric charge has__________?
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A. an electric field

B. a magnetic field

C. both A. and (6)

D. none of the above

78. The dielectric constant (relative permittivity) of glass is given by___________?
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A. 5 to 100

B. 0.1 to 0.4

C. 2.0 to 4.0

D. 0.5 to 1.0

79. A closed surface contains two equal and opposite charges. The net electric flux from the surface will be________________?
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A. positive

B. zero

C. negative

D. data is insufficient

80. An uncharged conductor is placed near a charged conductor, then_____________?
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A. the uncharged conductor is attracted first and then charged by induction

B. it remains as such

C. the uncharged conductor gets charged by induction and then attracted towards the charging body

D. the uncharged conductor gets charged by conduction

81. Air capacitors are generally available in the range_________?
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A. 100 to 900 pF

B. 20 to 100 pF

C. 1 to 20 pF

D. 10 to 400 pF
82. The inverse of capacitance is called_______________?
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A. conductance

B. reluctance

C. elastance

D. susceptance

83. The ohmmeter reading for a short circuited capacitor is____________?
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A. few megohms

B. zero

C. infinity

D. few kilo ohms

84. An electrolytic capacitor is generally made to provide__________?
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A. variable capacitance

B. low capacitance

C. fixed capacitance

D. large value of capacitance
85. capacitors can be used only for D.C ?
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A. Electrolytic

B. Paper

C. Mica

D. Air

86. Electric field intensity is a quantity_____________?
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A. scalar

B. vector

C. both A. and (6)

D. none of the above

87. Which of the following capacitors has relatively shorter shelf life____________?
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A. Ceramic capacitor

B. Electrolytic capacitor

C. Paper capacitor

D. Mica capacitor

88. at a point may be defined as equal to the lines of force passing normally through a unit cross section at that point ?
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A. None of the above

B. Magnetic flux density

C. Electric intensity

D. Electric flux

89. In order to remove static electricity from machinery___________?
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A. ground the framework

B. construct insulated cabins

C. insulate the machinery

D. humidify the surroundings

90. When a dielectric is placed in an electric field the field strength____________?
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A. reduces to zero

B. increases

C. decreases

D. remain unchanged

91. Two similar charges each of one coulomb placed in air one meter apart repel each other with a force______________?
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A. 9.2 x 104N

B. 9 x 107N

C. 9 x 109N

D. 9 x 109N
92. The number of Faraday tubes of flux passing through a surface in an electric field is called____________?
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A. electric charge density

B. electric flux density

C. electric flux

D. magnetic flux density

93. In a capacitor the electric charge is stored in____________?
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A. metal plates

B. dielectric

C. both (A) and (B)

D. none of the above

94. The direction of electric field due +0 positive charge is ___________?
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A. away from the charge

B. towards the charge

C. both A. and (6)

D. none of the above

95. A capacitor consists of_____________?
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A. two conductors only

B. two conductors separated by an insulator

C. two insulators only

D. two insulators separated by a conductor

96. Which is the most superior dielectric out of the following ?
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A. Glass

B. Bakelite

C. Paper

D. Air

97. Potential difference is the work done in moving unit positive charge form one point to another________________?
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A. in the direction of electric intensity

B. against electric intensity

C. in the direction of electric flux

D. in any direction

98. Voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater than air. What will be the value of dielectric constant ________?
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A. 50

B. 200

C. 100

D. 150

99. Capacitance increases with_____________?
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A. increase in plate area and decrease in distance between the plates

B. decrease in plate area and value of applied voltage

C. reduction in plate area and distance between the plates

D. increase in plate area and distance between the plates

100. Electric flux linked with a surface will be maximum when____________?
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A. The surface is held parallel to the electric field

B. The surface is held perpendicular to the electric field

C. The surface makes an angle of 45with the field

D. All of the above