In this article, we shared the electrostatics objective questions and answers for electrical and electronics engineers.
Electrostatics Objective Questions
The below list provides all the multiple-choice questions related to electrostatics.
Answers are available at the bottom of the article.
1. Which is the most superior dielectric out of the following?
| A) | Glass |
| B) | Air |
| C) | Paper |
| D) | Bakelite |
2. Which of the following statements associated with capacitors is wrong?
| A) | A finite amount of energy can be stored in a capacitor even if the current through the capacitor is zero, such as when the voltage across it is a constant. |
| B) | A capacitor resists an abrupt change in the voltage across it in a manner analogous to the way a spring resists abrupt change in its displacement |
| C) | A capacitor resists an abrupt change in the current flowing through it. |
| D) | lt is impossible to change the voltage across a capacitor even if the current through the capacitor by a finite amount in zero time, for this requires infinite current through the capacitor. |
3. Two capacitors each having capacitance C and break down voltage V are joined in series. The capacitance and break down voltage of the combination is
| A) | 2C and V |
| B) | C/2 and V/2 |
| C) | C/2 and 2V |
| D) | 2C and 2V |
4. A capacitance of 1 μF equals
| A) | 10-8 F |
| B) | 10-12 F |
| C) | 10-6 F |
| D) | 10-4 F |
5. Dielectric constant for mica is nearly
| A) | 1 to 2 |
| B) | 100 |
| C) | 3 to 8 |
| D) | 200 |
6. The units of capacitance are
| A) | coulombs/volt |
| B) | volts/coulomb |
| C) | ohms |
| D) | henry/Wb |
7. Which of the following expression is correct for electric field strength?
| A) | E = πD2 |
| B) | E = D/ε |
| C) | E = D2/ε |
| D) | E = πD |
8. A condenser suitable for D.C. only is
| A) | metallic paper capacitor |
| B) | metallic plate variable gang condenser |
| C) | oil impregrated paper condenser |
| D) | poled aluminium electrolytic condenser |
9. Dielectric strength____ with increasing thickness
| A) | increases |
| B) | decreases |
| C) | none of these answers |
| D) | remains unaltered |
10. The force between two charges is 120 N. If the distance between the charges is doubled, the force will be
| A) | 80N |
| B) | 15N |
| C) | 40N |
| D) | 60N |
11. Which of the following capacitors will have the least variation?
| A) | Silver plated mica capacitor |
| B) | None of these answers |
| C) | Ceramic capacitor |
| D) | Paper capacitor |
12. The capacitance of a capacitor is not affected by
| A) | thickness of plates |
| B) | all of these answers |
| C) | area of plates |
| D) | distance between plates |
13. Paper condenser is
| A) | usually of fixed value |
| B) | electrolytic condenser |
| C) | always polarised |
| D) | a variable condenser |
14. In a concentric cable capacitor the diameters of the inner and outer cylinders are 3 and 10 mm respectively. If εr for insulation is 3, find its capacitance per meter.
| A) | 118.8 pF |
| B) | 138.8 pF |
| C) | 100 pF |
| D) | 110 pF |
15. Inside a charge hollow conducting sphere, the potential will be
| A) | Proportional to the distance from the center |
| B) | Constant |
| C) | None of these answers |
| D) | Inversely proportional to the distance from the center |
16. 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
| A) | 10 times greater than before |
| B) | 5 times smaller than before |
| C) | 25 times larger than before |
| D) | 5 times greater than before |
17. A capacitance is a circuit component that opposes the change in circuit
| A) | impedance |
| B) | current |
| C) | none of these answers |
| D) | voltage |
18. The charge on an isolated conductor resides
| A) | none of these answers |
| B) | inside the conductor. |
| C) | at the conductor surface. |
| D) | partly at the surface and partly inside the conductor. |
19. In a capacitive circuit
| A) | an increase in applied voltage makes a capacitor charge |
| B) | none of these answers |
| C) | decrease in applied voltage makes a capacitor charge |
| D) | a steady value of applied voltage causes discharge |
20. The unit of dielectric strength is given by
| A) | V/m |
| B) | V2/m |
| C) | m/V2 |
| D) | m/V |
21. A unit tube of flux is known as____ tube
| A) | Newton |
| B) | Michale |
| C) | Faraday |
| D) | None of these answers |
22. The total deficiency or excess of electrons in a body is known as
| A) | voltage |
| B) | current |
| C) | charge |
| D) | potential gradient |
23. The presence of an uncharged conductor near a charged one increases the
| A) | all of these answers |
| B) | the potential of the charged conductor |
| C) | charge of the charged conductor |
| D) | the capacity of the charged conductor |
24. Out of the following capacitors of identical rating which one will have the smallest dimensions?
| A) | Paper capacitor |
| B) | Ceramic capacitor |
| C) | Mica capacitor |
| D) | Aluminum foil capacitor |
25. What is the value of capacitance that must be connected in parallel with 50 pF condenser to make an equivalent capacitance of 150 pF?
| A) | 200 pF |
| B) | 100 pF |
| C) | 150 pF |
| D) | 50 pF |
26. A mica capacitor and a ceramic capacitor both have the same physical dimensions. Which will have more value of capacitance?
| A) | It depends on the applied voltage |
| B) | Mica capacitor |
| C) | Ceramic capacitor |
| D) | Both will have identical values of capacitance |
27. The units of volume charge density are
| A) | Coulomb / meter |
| B) | Coulomb / meter2 |
| C) | Coulomb / meter3 |
| D) | Coulomb / meter4 |
28. In a multilayer dielectric material on either side of a boundary.
| A) | the normal component of electrical displacement is same. |
| B) | the tangential component of electrical field is necessarily zero. |
| C) | the normal component of electrical field is same. |
| D) | the tangential component of electrical displacement is necessarily zero. |
29. An ideal voltage source will charge an ideal capacitor
| A) | exponentially |
| B) | in infinite time. |
| C) | instantaneously. |
| D) | none of these answers |
30. A variable capacitance is one whose capacitance
| A) | can be changed manually or by mechanical means |
| B) | changes with temperature |
| C) | changes with time |
| D) | changes with voltage |
31. Which of the following statements is correct?
| A) | The electrolytic capacitor must be connected in the correct polarity |
| B) | Air capacitors have a blackband to indicate the outside foil |
| C) | Mica capacitors are available in capacitance value of 1 to 10 μF |
| D) | Ceramic capacitors must be connected in the correct polarity |
32. Tangential component of the electric field on a perfect conductor will be
| A) | same as the normals field component and 90° out of phase. |
| B) | infinite. |
| C) | zero. |
| D) | same as the normal component but 180° out of phase. |
33. In the case of a lossy capacitor, its series equivalent resistance value will be
| A) | large |
| B) | zero |
| C) | very small |
| D) | small |
34. A capacitor of 80 μF is charged to a potential difference (p.d.) of 250V. The charge acquired by it is
| A) | 0.4 C |
| B) | 0.2 C |
| C) | 0.02 C |
| D) | 0.3 C |
35. The potential inside a charged hollow sphere is
| A) | none of these answers |
| B) | zero. |
| C) | less than that on the surface. |
| D) | same as that on the surface. |
36. An, electrolytic capacitor is generally made to provide
| A) | fixed capacitance |
| B) | low capacitance |
| C) | variable capacitance |
| D) | large value of capacitance |
37. The value of one Farad in e.s.u. will be
| A) | 3 x 1010 |
| B) | 1/9 X 1010 |
| C) | 1/3 X 1010 |
| D) | 9 x 1011 |
38. One volt is the same as
| A) | one joule |
| B) | one joule/coulomb |
| C) | one coulomb |
| D) | one coulomb/joule |
39. Electric flux in coulombs emanating from any surface of a cube containing C coulombs of charge at its center is
| A) | Q/6E |
| B) | 4πQ/6E |
| C) | Q/6 |
| D) | Q/4π |
40. Dielectric strength of the medium
| A) | increases with rise in temperature |
| B) | increases with moisture content |
| C) | none of these answers |
| D) | is same for all insulating materials |
41. Capacity of a parallel plate condenser can be increased by
| A) | Decreasing the distance between the plates |
| B) | Decreasing the thickness of the plates |
| C) | Increasing the distance between the plates |
| D) | Increasing the thickness of the plates |
42. ____ capacitors can be used only for D.C.
| A) | Electrolytic |
| B) | Mica |
| C) | Paper |
| D) | Air |
43. The unit of capacitance is
| A) | ohm |
| B) | henry |
| C) | farad/m |
| D) | farad |
44. If a current of 2 A passes through a lamp for 200 seconds, the number of coulombs of charge passing through the lamp in that time will be
| A) | 200 C |
| B) | 300 C |
| C) | 400 C |
| D) | 100 C |
45. The relation between the breakdown voltage V and the thickness (t) of the dielectric is given by V =At2/3, where A is a constant depending on the nature of the medium and also on the thickness t. The above statement is known as
| A) | Kirchhoff’s law |
| B) | Baur’s law |
| C) | Faraday’s law |
| D) | None of these answers |
46. Two plates of a parallel plate capacitor after being charged from a constant voltage source are separated apart by means of insulated handles, then the
| A) | voltage across the plates increases |
| B) | charge on the capacitor increases |
| C) | voltage across the plates decreases |
| D) | charge on the capacitor decreases |
47. The relation between electric polarization and susceptibility indicates that electric polarization is
| A) | proportional to square root of susceptibility. |
| B) | proportional to susceptibility. |
| C) | inversely proportional to susceptibility. |
| D) | independent of susceptibility. |
48. If a third equal and similar charge is placed between two equal and similar charges, then this third charge will
| A) | move out of the field of influence of the two charges |
| B) | not be in equilibrium |
| C) | be in unstable equilibrium |
| D) | remain in stable equilibrium |
49. The line of force due to charged particles are
| A) | always curved |
| B) | none of these answers |
| C) | always straight |
| D) | sometimes curved |
50. The unit of electric intensity is
| A) | newton/coulomb. |
| B) | joules/coulomb. |
| C) | volt/meter. |
| D) | both (B) and (C). |
51. Electric intensity at any point in an electric field is equal to the____ at that point.
| A) | magnetic flux density |
| B) | electric flux |
| C) | potential gradient |
| D) | none of these answers |
52. In the case of a lossy capacitor, its series equivalent resistance value will be
| A) | negligible |
| B) | small |
| C) | very small |
| D) | large |
53. If three 15 μF capacitors are connected in series, the net capacitance is
| A) | 45 μF |
| B) | 5 μF |
| C) | 50 μF |
| D) | 30 μF |
54. A field line and an equipotential surface are
| A) | none of these answers |
| B) | always parallel |
| C) | inclined at any angle θ |
| D) | always at 90° |
55. Which of the following capacitors has a relatively shorter shelf life?
| A) | Paper capacitor |
| B) | Electrolytic capacitor |
| C) | Ceramic capacitor |
| D) | Mica capacitor |
56. Which of the following capacitor is preferred in the case of single-phase motor?
| A) | Ceramic capacitor |
| B) | Paper capacitor |
| C) | Electrolytic capacitor |
| D) | Mica capacitor |
57. Which one of the following statements does not state that the electrostatic field is conservative?
| A) | The potential difference between two points is zero. |
| B) | The work done in a closed path inside the field is zero. |
| C) | The electrostatic field is a gradient of a scalar potential |
| D) | The Curl of E is identically zero |
58. Three capacitors each of breakdown voltage 500 V are connected in parallel. The breakdown rating of the combination will be
| A) | 707 V |
| B) | 1,000 V |
| C) | 2,500 V |
| D) | 500 V |
59. For closer tolerances which of the following capacitors is usually preferred?
| A) | None of these answers |
| B) | Paper capacitor |
| C) | Mica capacitor |
| D) | Ceramic disc capacitor |
60. Which capacitor will be physically smaller for the same ratings?
| A) | Ceramic capacitor |
| B) | None of these answers |
| C) | Paper capacitor |
| D) | Both will be of equal size |
61. A large sphere P of radius R is charged positively. It is momentarily connected to a small sphere Q of radius r. The two spheres now have the same
| A) | Charge |
| B) | Energy |
| C) | Potential |
| D) | Electric field |
62. The capacity of a spherical conductor is 1 picofarad then its diameter would be
| A) | 1.8 xmeter |
| B) | 1.8 x 104 meter |
| C) | 1.8 x 103 meter |
| D) | 1.8 x 1010 meter |
63. Dielectric strength of a material depends on
| A) | all of these answers |
| B) | thickness |
| C) | temperature |
| D) | moisture content |
64. A parallel plate capacitor has a capacitance of 10 μF. If the linear dimensions of the plates are doubled and the separation between them has also doubled the value of the capacitor would be
| A) | 10 μF |
| B) | 5 μF |
| C) | 20 μF |
| D) | 40 μF |
65. Electric potential at the center of a charged conductor is
| A) | Zero |
| B) | Half of that on the surface |
| C) | Same as that on the surface |
| D) | Twice as that on the surface |
66. A capacitor having a capacitance of 5 μF is charged to a potential difference of 10,000 V. The energy stored in the capacitor is
| A) | 150 joules |
| B) | 200 joules |
| C) | 250 joules |
| D) | 50 joules |
67. ____capacitors are used in transistor circuits.
| A) | Electrolytic |
| B) | Ceramic |
| C) | Paper |
| D) | Air |
68. What will happen to an insulating medium if voltage more than the breakdown voltage is applied to it?
| A) | It will get punctured or cracked |
| B) | It will melt |
| C) | It will become magnetic |
| D) | Its molecular structure will get changed |
69. The ratio of electric flux density to electric field intensity is called____ of the medium
| A) | reluctance |
| B) | permeability |
| C) | capacitance |
| D) | permittivity |
70. The property of a capacitor to store electricity is called its
| A) | none of these answers |
| B) | capacitance |
| C) | charge |
| D) | energy |
71. A capacitor having capacitance of 40 μF is connected across 250 V D.C. source. The charging current will be least
| A) | initially |
| B) | when capacitor is almost 25% charged |
| C) | when capacitor is half charged |
| D) | when capacitor is fully charged |
72. Which of the following statements is correct?
| A) | Air capacitors have a black band to indicate the outside foil |
| B) | Ceramic capacitors must be connected in correct polarity |
| C) | Mica capacitors are available in capacitance values of 5 to 20 μF |
| D) | Electrolytic capacitors must be connected in correct polarity |
73. The electric field at a point situated at distance cl from the straight charged conductor is
| A) | none of these answers |
| B) | inversely proportional to d2 |
| C) | inversely proportional to d |
| D) | proportional to d |
74. 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.
| A) | 63 |
| B) | 42 |
| C) | 37 |
| D) | 73 |
75. The power dissipated in a pure capacitor is
| A) | both proportional to applied voltage and proportional to value of capacitance |
| B) | zero |
| C) | proportional to value of capacitance |
| D) | proportional to applied voltage |
76. Three capacitors each of the capacity C are given. The resultant capacity 2/3 C can be obtained by using them
| A) | two in series and third in parallel across this combination |
| B) | all in parallel |
| C) | all in series |
| D) | two in parallel and third in series with this combination |
77. Dielectric strength of mica is
| A) | 50 to 200 kV/mm |
| B) | 300 to 500 kV/mm |
| C) | 30 to 50 kV/mm |
| D) | 10 to 20 kV/mm |
78. When a dielectric slab is introduced in a parallel plate capacitor, the potential difference between plates will
| A) | remain uncharged |
| B) | become zero |
| C) | decrease |
| D) | increase |
79. The dielectric constant (relative permittivity) of glass is given by
| A) | 0.1 to 0.4 |
| B) | 2.0 to 4.0 |
| C) | 5 to 10 |
| D) | 0.5 to 1.0 |
80. A dielectric material must be
| A) | insulator |
| B) | resistor |
| C) | good conductor |
| D) | semi-conductor |
81. Check the correct relation
| A) | Potential = capacity x charge |
| B) | Potential = charge/capacity |
| C) | Charge = potential/capacity |
| D) | Capacity = potential x charge |
82. It was suggested by ____that the electric field should be imagined to be divided into tubes of force containing a fixed number of lines of force.
| A) | Faraday |
| B) | Newton |
| C) | All of these answers |
| D) | Kelvin |
83. Permittivity is expressed in
| A) | Farad/metre |
| B) | Weber/sq-m |
| C) | Farad/sq-m |
| D) | Weber/metre |
84. Which of the following statement(s) is/are valid in the case of conductors in electrostatic fields?
| A) | All of these answers |
| B) | The electric field intensity at the surface of a conductor is everywhere directed normal to that surface. |
| C) | The surface of a conductor is an equipotential surface. |
| D) | The electric field intensity inside a conductor is zero. |
85. Dielectric strength of a material depends on
| A) | all of these answers |
| B) | temperature. |
| C) | moisture content. |
| D) | thickness. |
86. If AC voltage is applied to a capacitive circuit, the alternating current can flow in the circuit because
| A) | discharge current can flow |
| B) | varying voltage produces the charging and discharging currents |
| C) | of high peak value |
| D) | charging current can flow |
87. Internal heating of a capacitor is usually attributed to
| A) | electron movement |
| B) | plate vibration |
| C) | leakage resistance |
| D) | dielectric charge |
88. The condensers of 20 μF and 40 μF capacitance are connected in series across a 90 V supply.
After charging, they are removed from the supply and are connected in parallel with positive terminals connected together and similarly the negative terminals.
Then the voltage across them will be
| A) | 60 V |
| B) | 40 V |
| C) | 90 V |
| D) | 20 V |
89. When a dielectric is placed in an electric field the field strength
| A) | reduces to zero |
| B) | remain unchanged |
| C) | increases |
| D) | decreases |
90. The electric field between the two spheres of a charged spherical condenser
| A) | Is constant |
| B) | Decreases with distance from the center |
| C) | Is zero |
| D) | Increases with distance from the center |
91. ____at a point is equal to the negative potential gradient at that point.
| A) | Magnetic flux density |
| B) | Magnetic flux |
| C) | Electric intensity |
| D) | Electric flux |
92. Which of the following material has the least value of dielectric constant?
| A) | Paper |
| B) | Oil |
| C) | Glass |
| D) | Ceramics |
93. The electric field intensity at a point situated at a distanced from a straight charged conductor is proportional to
| A) | d |
| B) | 1/d2 |
| C) | 1/d |
| D) | d2 |
94. “The total electric flux through any closed surface surrounding charges is equal to the amount of charge enclosed”. The above statement is associated with
| A) | Coulomb’s square law |
| B) | Maxwell’s first law |
| C) | Gauss’s law |
| D) | Maxwells second law |
95. A medium behaves like dielectric when the
| A) | displacement current is much greater than the conduction current. |
| B) | displacement current is just equal to the conduction current. |
| C) | displacement current is almost negligible. |
| D) | displacement current is less than the conduction current. |
96. Air capacitors are generally available in the range
| A) | 10 to 400 pF |
| B) | 20 to 100 pF |
| C) | 1 to 20 pF |
| D) | 100 to 900 pF |
97. When the dielectric is homogeneous, the potential gradient is
| A) | any of these answers |
| B) | zero |
| C) | uniform |
| D) | non-uniform |
98. Inside a hollow conducting sphere
| A) | electric field is zero. |
| B) | electric field changes with the magnitude of the charge given to the conductor. |
| C) | electric field is a non-zero constant. |
| D) | electric field changes with distance from the centre of the sphere. |
99. The capacitor preferred for high-frequency circuits is
| A) | none of these answers |
| B) | mica capacitor |
| C) | air capacitor |
| D) | electrolytic capacitor |
100. Putting the plates of a charged capacitor apart
| A) | Decreases the potential difference |
| B) | Does not effect potential difference |
| C) | Increases the potential difference |
| D) | Increases the capacitance |
101. The capacitor preferred for high-frequency circuits is
| A) | none of these answers |
| B) | mica capacitor |
| C) | electrolytic capacitor |
| D) | air capacitor |
102. The dielectric strength of a medium is usually expressed in
| A) | N/mm |
| B) | c/m2 |
| C) | kV/mm |
| D) | J/mm |
103. The voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater than air. What will be the value of the dielectric constant?
| A) | 200 |
| B) | 100 |
| C) | 50 |
| D) | 150 |
104. Which of the following capacitors are preferred for high-frequency circuits?
| A) | Mica capacitor |
| B) | none of these answers |
| C) | Air capacitor |
| D) | Electrolytic capacitor |
105. A paper capacitor is usually available in the form of
| A) | rolled foil |
| B) | tubes |
| C) | disc |
| D) | meshed plates |
106. An electric dipole is placed in an electric field generated by a point charge
| A) | The net electric force on the dipole may be zero |
| B) | The torque on the dipole due to the field may be zero |
| C) | The net electric force on the dipole must be zero |
| D) | The torque on the dipole due to the field must be zero |
107. The direction of the lines of force at any point is the direction along which a unit ____charge placed at that point would move if free to do so
| A) | negative |
| B) | both negative & positive |
| C) | positive |
| D) | none of these answers |
108. The voltage applied across a dielectric produces an electrostatic field 50 times greater than air. The dielectric constant of the dielectric will be
| A) | 20 |
| B) | 50 |
| C) | 5 |
| D) | 10 |
109. If an ohmmeter reading immediately goes practically to zero and stays there while checking a capacitor, the capacitor is
| A) | short-circuited. |
| B) | leaky. |
| C) | open-circuited. |
| D) | satisfactory. |
110. The potential difference across a capacitor of capacitance 20 μF is increased uniformly from 0 to 240 V in 1 second. The charging current will be
| A) | 1.2mA |
| B) | 12mA |
| C) | 9.6mA |
| D) | 4.8mA |
111. Energy density in a static electric field is given by
| A) | W = 1/2CV2 |
| B) | W = 1/2QV |
| C) | W = 1/2DE |
| D) | W = 1/2∈E2V |
112. The point charges Q and 2Q are placed at a distance R apart. Where should a third point charge be placed, So that it is in equilibrium
| A) | At a point on the left of Q |
| B) | Between Q and 2Q |
| C) | At a point on the right of 2Q |
| D) | None of these answers |
113. Which of the following medium will have the highest value of relative permittivity?
| A) | Glass |
| B) | Mica |
| C) | Paper |
| D) | Water |
114. If an ohmmeter reading immediately goes practically to zero and stays there, the capacitor is
| A) | lossy |
| B) | charged |
| C) | short-circuited |
| D) | satisfactory |
115. A glass slab is put within the plates of a charged parallel plate condenser. Which of the following quantities does not change?
| A) | Charge |
| B) | Energy of the condenser |
| C) | Capacity |
| D) | Intensity of electric field |
116. The dissipation factor of good dielectric is of the order of
| A) | 0.1 |
| B) | 0.02 |
| C) | 0.0002 |
| D) | 0.002 |
117. “The surface integral of the normal component of the electric displacement D over any closed surface equals the charge enclosed by the surface”. The above statement is associated with
| A) | Kirchhoff’s law |
| B) | Faraday’s law |
| C) | Lenz’s law |
| D) | Gauss’s law |
118. The electric potential due to an electric dipole of length l at a point distance r away from it will be doubled if the
| A) | r is halved. |
| B) | r is doubled. |
| C) | l is halved. |
| D) | length l of the dipole is doubled. |
119. The bridge used for the measurement of the value of the capacitance is
| A) | Schering bridge |
| B) | Wien’s bridge |
| C) | Hay’s bridge |
| D) | Wheatstone bridge |
120. ___ at a point may be defined as equal to the lines of force passing normally through a unit crosssection at that point.
| A) | None of these answers |
| B) | Magnetic flux density |
| C) | Electric flux |
| D) | Electric intensity |
121. When 4 volts e.m.f is applied across a 1 farad capacitor, it will store the energy of
| A) | 2 joules |
| B) | 8 joules |
| C) | 4 joules |
| D) | 6 joules |
122. The equipotential line due to point charge Q is
| A) | A straight line |
| B) | A circle |
| C) | A hyperbola |
| D) | An ellipse |
123. Two capacitors each having capacitance C and breakdown voltage V are joined in series. The capacitance and breakdown voltage of the combination will be
| A) | 2 C and 2 V |
| B) | C/2 and V/2 |
| C) | C/2 and 2 V |
| D) | 2 C and V/2 |
124. The capacitance G is charged through a resistance R. The time constant of the charging circuit is given by
| A) | RC |
| B) | C/R |
| C) | 1/RC |
| D) | R/C |
125. If the sheet of bakelite is inserted between the plates of an air capacitor, the capacitance will
| A) | increase |
| B) | become zero |
| C) | decrease |
| D) | remains unchanged |
126. A variable capacitor of 100 μF carries a charge of 0.35 μC. The capacitance is subsequently reduced to 40 pF. The voltage appearing across the capacitor after reduction of its capacitance will be
| A) | 2000 V |
| B) | 1500V |
| C) | 4350V |
| D) | 8750 V |
127. For which of the following parameter variation, the capacitance of the capacitor remains unaffected?
| A) | Distance between plates |
| B) | Area of the plates |
| C) | Nature of dielectric |
| D) | Thickness of the plates |
128. In a capacitor, the electric charge is stored in
| A) | metal plates |
| B) | none of these answers |
| C) | both metal plates and dielectric |
| D) | dielectric |
129. Two spheres of radii r1 and r2 are connected by a conducting wire. Each of the spheres has been given a charge Q. Now
| A) | larger sphere will have greater potential. |
| B) | smaller sphere will have zero potential. |
| C) | both of the spheres will have same potential. |
| D) | larger sphere will have smaller potential. |
130. Electric field intensity is a____ quantity
| A) | vector |
| B) | scalar |
| C) | both scalar and vector |
| D) | none of these answers |
131. If the dielectric of a capacitor is replaced by a conducting material the
| A) | plates will get short circuited. |
| B) | capacitor can store infinite charge |
| C) | capacitance will become very high. |
| D) | capacitor will get heated up owing to eddy currents. |
132. Which of the following capacitors will have the least value of breakdown voltage?
| A) | Paper |
| B) | Ceramic |
| C) | Electrolytic |
| D) | Mica |
133. In a cable capacitor, voltage gradient is maximum at the surface of the
| A) | insulator |
| B) | conduction |
| C) | sheath |
| D) | earth |
134. Paper capacitors usually have tolerance of
| A) | ±10% |
| B) | ±5% |
| C) | ±15% |
| D) | ±20% |
135. A capacitor charged to 200 V has 2000 μC of charge. The value of capacitance will be
| A) | 100 μF |
| B) | 10 μF |
| C) | 1000 μF |
| D) | 10 F |
136. The dissipation factor of a good dielectric is of the order of
| A) | 0.2 |
| B) | 0.002 |
| C) | 0.02 |
| D) | 0.0002 |
137. During the dielectric breakdown of a capacitor
| A) | electrons are scattered. |
| B) | electrons cease to move from one plate to another. |
| C) | permanent conduction path is established between capacitor plates. |
| D) | none of these answers |
138. 1 volt/metre is same as
| A) | 1 metre/coulomb |
| B) | 1 joule/coulomb |
| C) | 1 newton metre |
| D) | 1 newton/metre |
139. Which medium has the least dielectric strength?
| A) | Glass |
| B) | Air |
| C) | Quartz |
| D) | Paraffin wax |
140. A potential of 400 V is applied to a capacitor, the plates of which are 4 mm apart. The strength of the electric field is
| A) | 100 kV/m |
| B) | 10 kV/m |
| C) | 2 kV/m |
| D) | 5 kV/m |
141. Fields are said to be circularly polarized if their magnitudes are
| A) | Equal and they differ in phase by ± 90°. |
| B) | Unequal and they differ in phase by ±90°. |
| C) | Equal any they are in phase. |
| D) | Unequal and they are in phase. |
142. A soap bubble is given a negative charge then its radius
| A) | Increases |
| B) | Remains unchanged |
| C) | Decreases |
| D) | None of these answers |
143. The area of plates of the parallel plate capacitor, to obtain a capacity of 0.3 x 10-3 μF if they are separated by a distance of 10mm and a dielectric between them of permittivity = 2.5, will be
| A) | 0.1 m2 |
| B) | 0.135 m2 |
| C) | 0.125 m2 |
| D) | 0.235 m2 |
144. The ohmmeter reading for a short-circuited capacitor is
| A) | few kilo ohms |
| B) | few megaohms |
| C) | zero |
| D) | infinity |
145. The capacitance of a capacitor is influenced by
| A) | plate area |
| B) | plate separation |
| C) | none of these answers |
| D) | all of these answers |
| E) | nature of dielectric |
146. The capacity of the capacitor bank used in power factor correction is expressed in terms of
| A) | kVA |
| B) | volts |
| C) | kVAR |
| D) | kW |
147. The direction of electric field due to positive charge is
| A) | both away from the charge and towards the charge |
| B) | none of these answers |
| C) | away from the charge |
| D) | towards the charge |
148. Electric displacement is a____quantity
| A) | none of these answers |
| B) | scalar |
| C) | both scalar and vector |
| D) | vector |
149. The potential gradient at which the dielectric of the condenser just gets punctured is called
| A) | Dielectric constant |
| B) | Dielectric number |
| C) | Dielectric strength |
| D) | Dielectric resistance |
150. The energy of a charged capacitor resides in
| A) | Neither in electric nor magnetic field |
| B) | The magnetic field only |
| C) | Both the electric and magnetic fields |
| D) | The electric field only |
151. The absolute permittivity of free, space is given by
| A) | 8.854 x 10-9 F/m |
| B) | 8.854 x 10-10 F/m |
| C) | 8.854 x 10-11 F/m |
| D) | 8.854 x 10-11 F/m |
152. The ability of charged bodies to exert force on one another is attributed to the existence of
| A) | electrons |
| B) | electric field |
| C) | neutrons |
| D) | protons |
153. Coulomb’s law for the force between electric charges most closely resembles with
| A) | Law of conservation of energy. |
| B) | Newton’s law of gravitation |
| C) | Gauss’s theorem. |
| D) | Newton’s law of motion. |
154. Electric field intensity between plates of a parallel plate condenser is E. Now if a dielectric of medium of dielectric constant ϵ is introduced between the plates, the electric field intensity will become
| A) | ϵE |
| B) | E/ϵ |
| C) | √(ϵE) |
| D) | √(E/ϵ) |
155. In order to remove static electricity from machinery
| A) | ground the framework |
| B) | humidify the surroundings |
| C) | insulate the machinery |
| D) | construct insulated cabins |
156. Electric intensity (E) at any point in an electric field is equal to
| A) | potential gradient |
| B) | (potential gradient)2 |
| C) | (potential gradient)1/2 |
| D) | (potential gradient)1/3 |
157. The inverse of capacitance is called
| A) | reluctance |
| B) | susceptance |
| C) | conductance |
| D) | elastance |
158. To prevent the generation of static charges on rubber or flat leather
| A) | surface is moistened |
| B) | oil compound dressing is done |
| C) | talcum powder is sprayed on the surface |
| D) | conductive dressing is done |
159. Two conductors having the same type of charges are connected by a conducting wire. There would not be any change in the amount of charges on them if
| A) | They have the same amount of charge |
| B) | They have the same shape |
| C) | They have the same capacity |
| D) | They have the same potential |
160. Which of the following statements is incorrect?
| A) | The thinner the dielectric, the more the capacitance and the lower the voltage breakdown rating for a capacitor |
| B) | A capacitor can store charge because it has a dielectric between two conductors |
| C) | Capacitors in series provide less capacitance but a higher voltage breakdown rating for the combination |
| D) | A six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pF |
161. The electric field inside a perfectly conducting media is
| A) | zero. |
| B) | dependent upon the value of the charge. |
| C) | none of these answers |
| D) | infinite. |
162. In a charge-free space, Poisson’s equation results in which one of the following?
| A) | Laplace equation. |
| B) | Continuity equation. |
| C) | None of these answers |
| D) | Maxwell’s equation. |
163. Across the surface of a charged conductor, the electric
| A) | field is continuous |
| B) | potential is discontinuous |
| C) | field is discontinuous |
| D) | none of these answers |
164. The ratio of the charge stored by two metallic spheres raised to the same potential is 6. The ratio of the surface areas of the sphere is
| A) | 1/6 |
| B) | 36 |
| C) | 1/6 |
| D) | 6 |
165. Which of the following capacitors will have the least energy stored in it?
| A) | A 600 pF capacitor charged to 15 kV |
| B) | A 1 μF capacitor charged to 5 kV |
| C) | A 20 μF capacitor charged to 400 V |
| D) | Energy stored in each above will be same |
166. The electrostatic force between two charges of one coulomb each and placed at a distance of 0.5 m will be
| A) | 36 x 106 N |
| B) | 36 x 107 N |
| C) | 36 x 108 N |
| D) | 36 x 109 N |
167. The capacitance between two plates increases with
| A) | larger plate area, longer distance between plates and higher applied voltage |
| B) | larger plate area and shorter distance between plates |
| C) | shorter plate area and higher applied voltage |
| D) | shorter plate area and shorter distance between titen |
168. In a cable capacitor, voltage gradient is maximum at the surface of the
| A) | sheath. |
| B) | conductor. |
| C) | dielectric. |
| D) | earth. |
169. A capacitor stores 0.24 coulombs at 10 volts. Its capacitance is
| A) | 0.024 F |
| B) | 0.12 F |
| C) | 0.8 F |
| D) | 0.6 F |
170. In a parallel plate capacitor, a dielectric slab is introduced. Then the
| A) | all of these answers |
| B) | potential difference between the plates will decrease |
| C) | electric intensity will decrease. |
| D) | capacitance will increase |
171. The relative permittivity has the following units
| A) | no units |
| B) | Wb/m |
| C) | m/F |
| D) | F/m |
172. “The force of attraction or repulsion between two charges Q1 and Q2 at a distanced meters apart is proportional to the product of charges and inversely proportional to the square of the distance between the two charges”. The above statement is associated with
| A) | Lenz’s law |
| B) | Maxwell’s law |
| C) | Coulomb’s law |
| D) | Faraday’s law |
173. Two metal plates distance ‘d’ apart form a capacitor of value C farads. Another metal plate of thickness d/2 and of the same area is inserted in between these two plates, the capacitance of this three plate capacitor will be
| A) | 1/2 |
| B) | 1/4 |
| C) | 4 |
| D) | 2 |
174. ___capacitors are mainly used for radio-frequency tuning
| A) | Mica |
| B) | Electrolytic |
| C) | Paper |
| D) | Air |
175. Two electrons moving parallel to each other at the same velocity will
| A) | repel each other with the same force when moving in the same or opposite direction. |
| B) | repel each other less strongly when moving in same direction. |
| C) | attract each other if they move in the same direction. |
| D) | repel each other more strongly when moving in the same direction than when moving in opposite direction. |
176. A ceramic and a mica capacitor have the same physical dimensions. Which has the higher value of capacitance?
| A) | Both have identical value of capacitance |
| B) | Ceramic capacitor |
| C) | It is not possible to conclude on the basis of information supplied |
| D) | Mica capacitor |
177. A capacitor consists of
| A) | two conductors separated by an insulator |
| B) | two conductors only |
| C) | two insulators only |
| D) | two insulators separated by a conductor |
178. ___capacitors are used for audio frequency and radio frequency coupling and tuning
| A) | Air |
| B) | Ceramic |
| C) | Mica |
| D) | Plastic film |
179. The electric field intensity at a point situated 4 meters from a point charge is 200 N/C. If the distance is reduced to 2 meters. the field intensity will be
| A) | 400 N/C |
| B) | 600 N/C |
| C) | 1200 N/C |
| D) | 800 N/C |
180. While checking a good 0.05 μF capacitor by ohmmeter, it’s reading will
| A) | show high resistance momentarily and then a very low resistance |
| B) | none of these answers |
| C) | show low resistance momentarily and back off to a very high resistance. |
| D) | show a reading of 80 ohms |
181. If the dielectric of a capacitor is replaced by a conducting material
| A) | the capacitor will get heated up due to eddy currents |
| B) | the capacitor can store infinite charge |
| C) | the capacitance value of the capacitor will shoot upto very high value |
| D) | the plates will get short-circuited |
182. Mica capacitors are characterized by all of the following except
| A) | accurate value |
| B) | stable operation |
| C) | low losses |
| D) | low leakage reactance |
183. While testing a capacitor with ohm meter, if the capacitor shows charging, but the final resistance reading is appreciably less than normal, it can be concluded that the capacitor is
| A) | open circuited |
| B) | airight |
| C) | leaky |
| D) | short-circuited |
184. The sparking between two electrical contacts can be reduced by inserting a
| A) | capacitor in parallel with contacts |
| B) | none of these answers |
| C) | capacitor in series with each contact |
| D) | resistance in line |
185. Which of the following statement is true?
| A) | The current in the discharging capacitor decreases constantly |
| B) | The current in the discharging capacitor grows exponentially |
| C) | The current in the discharging capacitor decays exponentially |
| D) | The current in the discharging capacitor grows linearly |
186. The relation between the breakdown voltage V and the thickness t of the dielectric is given as V = At2/3 where A is a constant which depends on the nature and thickness of the medium. This statement is known as
| A) | Baur’s law. |
| B) | Coulomb’s law. |
| C) | none of these answers |
| D) | Gauss’s law. |
187. The breakdown voltage for paper capacitors is usually
| A) | more than 10000 volts |
| B) | 200 to 1600 volts |
| C) | Option 1 |
| D) | 2000 to 3000 volts |
188. A conducting body has a surface charge density of a coulombs/m2, the field intensity at its surface will be
| A) | σ / ε0 εr |
| B) | σ2 / ε0 εr |
| C) | ε0 εr |
| D) | σ3 / ε0 εr |
189. Energy stored in the electric field of a capacitor C when charged from a D.C source of voltage V is equal to____ joules
| A) | 1/2 CV2 |
| B) | 1/2 C2V |
| C) | CV2 |
| D) | C2V |
190. The capacitor charged up to 5 ms, as per the current profile given in the figure, is connected across an inductor of 0.6 mH. Then the value of voltage across the capacitor after 1 μs will approximately be
| A) | 18.8 V |
| B) | 23.5 V |
| C) | -30.6 V |
| D) | -23.5 V |
191. ___ is that property of a capacitor which delays any change of voltage across it
| A) | Capacitance |
| B) | Inductance |
| C) | Potential gradient |
| D) | None of these answers |
192. For preventing the generation of static charge on rubber or flat leather
| A) | oil compound dressing is done. |
| B) | any of these answers |
| C) | surface is moistened. |
| D) | conductive dressing is done. |
193. Electric field inside a hollow metallic charged sphere is
| A) | decreasing towards center |
| B) | increasing towards center |
| C) | none of these answers |
| D) | zero |
194. Which of the following statements is incorrect?
| A) | The stored energy in a capacitor increases with applied voltage |
| B) | The stored in a capacitor decreases with reduction in value of capacitance |
| C) | A wire cable has distributed capacitance between the conductors |
| D) | The leakage resistance of ceramic capacitors is generally high |
195. When the plate area of a parallel plate capacitor is increased keeping the capacitor voltage constant, the force between the plates
| A) | may increase or decrease depending on the metal making up the plates. |
| B) | decreases. |
| C) | increases. |
| D) | remains constant. |
196. Which of the following capacitors is marked for polarity?
| A) | Air |
| B) | Electrolytic |
| C) | Mica |
| D) | Paper |
197. The unit of polarization is the same as that of
| A) | dielectric flux. |
| B) | electric flux density D. |
| C) | charge. |
| D) | electric intensity E. |
198. The time constant of an R-C circuit is defined as the time during which capacitor charging voltage actually rises to____ percent of____ its value.
| A) | 63.2, initial |
| B) | 63.2, final |
| C) | 37, initial |
| D) | 37, final |
199. Which one of the following statements is correct? On a conducting surface boundary, electric field lines are
| A) | neither tangential nor normal. |
| B) | always normal. |
| C) | always tangential. |
| D) | at an angle depending on the field intensity. |
200. The number of Faraday tubes of flux passing through a surface in an electric field is called
| A) | electric flux |
| B) | magnetic flux density |
| C) | electric flux density |
| D) | electric charge density |
201. ___ field is associated with the capacitor.
| A) | Both Electric and Magnetic |
| B) | Electric |
| C) | none of these answers |
| D) | Magnetic |
202. A positively charged glass rod attracts an object. The object must be
| A) | Either negatively charged or neutral |
| B) | A magnet |
| C) | Neutral |
| D) | Negatively charged |
203. Which of the following materials has the highest value of dielectric constant?
| A) | Oil |
| B) | Glass |
| C) | Ceramics |
| D) | Vacuum |
204. An equipotential surface is one which has all points at____ potential
| A) | same |
| B) | none of these answers |
| C) | different |
| D) | zero |
205. The electric potential due to an electric dipole at an axial point distant r from the dipole is related to r as
| A) | r1 |
| B) | r-1 |
| C) | r2 |
| D) | r-2 |
206. The electric potential at the surface of an atomic nucleus (z = 50) of radius 9 x 10-15 m is
| A) | 80 volt |
| B) | 9 x 105 volt |
| C) | 9 volt |
| D) | 8 x 106 volt |
207. The phenomenon of an uncharged body getting charged merely by the nearness of a charged body is known as____
| A) | chemical effect |
| B) | photoelectric effect |
| C) | induction |
| D) | magnetic effect |
208. Which of the following is not a vector?
| A) | Angular momentum |
| B) | Linear momentum |
| C) | Electric field |
| D) | Electric potential |
209. “The surface integral of the normal component of the electric intensity E over a closed surface is equal to 1/Ε0 times the total charge inside it”. The above statement is known as
| A) | None of these answers |
| B) | Gauss’s theorem |
| C) | Lenz’s law |
| D) | Faraday’s law |
210. For making a capacitor, it is better to select a dielectric having
| A) | low permittivity |
| B) | high permittivity |
| C) | permittivity same as that of air |
| D) | permittivity slightly more than that of air |
211. If three 10 μF capacitors are connected in parallel, the net capacitance is
| A) | 20 μF |
| B) | 30 μF |
| C) | 50 μF |
| D) | 40 μF |
212. The potential gradient across the material of low permittivity is____ than across the material of high permittivity.
| A) | none of these answers |
| B) | both smaller and greater |
| C) | smaller |
| D) | greater |
213. Dielectric strength of a medium
| A) | is not affected by the moisture content |
| B) | decreases with the increase in thickness. |
| C) | increases with the increase in temperature. |
| D) | increases with moisture content. |
214. A charge which when placed in a vacuum from an equal and similar charge repels with a force of 9 x 103N, is known as
| A) | coulomb |
| B) | milli-coulomb |
| C) | micro-coulomb |
| D) | pico-coulomb |
215. Polarization of dielectric materials results in
| A) | absorption of electrons. |
| B) | production of eddy currents. |
| C) | creation of dielectric dipoles. |
| D) | release of protons. |
216. A single core cable used of 33000 V has a conductor diameter 10 mm and an internal diameter of the sheath of 25 mm. The maximum electrostatic stress in the cable is
| A) | 72 x 105 V/m |
| B) | 92 x 105 V/m |
| C) | 62 x 105 V/m |
| D) | 82 x 105 V/m |
217. The mass of an electron is equal to
| A) | 1.673 x 10-27 kg |
| B) | 9.11 x 10-31 kg |
| C) | 1.602 x 10-19 kg |
| D) | 9.11 x 10-20 kg |
218. lf C be the capacitance, V be the potential difference and I is the current, then 1/CV will have the unit of
| A) | power |
| B) | reactive power |
| C) | frequency |
| D) | time |
219. A capacitor in a circuit became hot and ultimately exploded due to wrong connections, which type of capacitor it could be?
| A) | Any of these answers |
| B) | Ceramic capacitor |
| C) | Electrolytic capacitor |
| D) | Paper capacitor |
220. A charge q is divided into two parts q1, and (q – q1) what is the ratio q/q1 so that the force between the two parts placed a given distance apart is maximum
| A) | 2 : 1 |
| B) | 1 : 4 |
| C) | 1 : 2 |
| D) | 1 : 1 |
221. An uncharged conductor is placed near a charged conductor, then
| A) | the uncharged conductor is attracted first and then charged by induction |
| B) | it remains as such |
| C) | the uncharged conductor gets charged by conduction |
| D) | the uncharged conductor gets charged by induction and then attracted towards the charging body |
222. In a capacitor, the electric charge is stored in
| A) | dielectric as well as metal plates |
| B) | dielectric |
| C) | none of these answers |
| D) | metal plates |
223. While testing a capacitor with ohmmeter, if the capacitor shows charging but the final resistance reading is appreciably less than normal the capacitor is
| A) | leaky. |
| B) | open circuited. |
| C) | short circuited. |
| D) | satisfactory. |
224. Capacitance increases with
| A) | increase in plate area and distance between the plates |
| B) | reduction in plate area and distance between the plates |
| C) | decrease in plate area and value of applied voltage |
| D) | increase in plate area and decrease in distance between the plates |
225. The value of dielectric constant for vacuum is taken as
| A) | 10 |
| B) | zero |
| C) | 4 |
| D) | 1 |
226. A hollow sphere of charge does not produce an electric field at any
| A) | None of these answers |
| B) | Interior point |
| C) | Outer point |
| D) | Surface point |
227. Which of the following capacitors can be used for temperature compensation ?
| A) | Paper capacitor |
| B) | Air capacitor |
| C) | None of these answers |
| D) | Ceramic capacitor |
228. The value of E within the field due to a point charge can be found with the help of
| A) | Faraday’s laws |
| B) | Kirchhoff’s laws |
| C) | Coulomb’s laws |
| D) | none of these answers |
229. When a capacitor undergoes a dielectric breakdown
| A) | permanent conduction path is established between plates |
| B) | electrons get scattered |
| C) | electrons cease to move from one plate to another |
| D) | dielectric stores energy rendering plates chargeless |
230. As per Coulomb’s law
| A) | F = Q1 Q2 / ε0 εr d2 |
| B) | F = Q1 Q2 / 4 π d2 |
| C) | F = Q1 Q2 / 4 π ε0 εr d2 |
| D) | F = Q1 Q2 / 4 π ε0 εr d |
231. If three capacitors C1, C2 and C3 of values of 1 μF, 2 μF, and 4 μF respectively are in series and connected across a potential of 230V, then charge on each capacitor is
| A) | 131 x 10-6 C |
| B) | 161 x 10-6 C |
| C) | 121 x 10-6 C |
| D) | 111 x 10-6 C |
232. If a 6 iF capacitor is charged to 200 V, the charge in coulombs will be
| A) | 900 μC |
| B) | 800 μC |
| C) | 1600 μC |
| D) | 1200 μC |
233. An electrolytic capacitor can be used for
| A) | none of these answers |
| B) | A.C. only |
| C) | both D.C. as well as AC. |
| D) | D.C. only |
234. A gang condenser is a
| A) | polarised capacitor |
| B) | none of these answers |
| C) | ceramic capacitor |
| D) | variable capacitor |
235. With steady D.C. voltage from a battery applied to a capacitance, after it charges to the battery voltage, the current in the circuit
| A) | depends on the current rating of the battery |
| B) | is smaller for larger values of capacitance |
| C) | is greater for larger values of capacitance |
| D) | is zero for any capacitance value |
236. The relative permittivity of free space is given by
| A) | 1000 |
| B) | 100 |
| C) | 10 |
| D) | 1 |
237. For removing static charge from machinery the
| A) | insulated cabins are constructed |
| B) | any of these answers |
| C) | framework is earthed. |
| D) | machinery is insulated. |
238. Equal charges are given to two spheres of different radii. The potential will
| A) | Be equal on both the sphere |
| B) | None of these answers |
| C) | Be more on the bigger sphere |
| D) | Be more on the smaller sphere |
239. A region around a stationary electric charge lias
| A) | an electric field |
| B) | both an electric field and a magnetic field |
| C) | none of these answers |
| D) | a magnetic field |
240. A capacitor consists of two
| A) | conductors separated by an insulator |
| B) | ceramic plates and one mica disc |
| C) | insulators separated by a dielectric |
| D) | silver-coated insulators |
241. For a good 0.05 μF capacitor ohmmeter reading should
| A) | show high resistance momentarily and then a very low resistance |
| B) | not move at all |
| C) | show low resistance momentarily and back off to a very high resistance |
| D) | go quickly to 50 ohm approximately and remain there |
242. Two copper spheres A (hollow) and B (solid) are of same diameter and are charged to the same potential.
| A) | None of the sphere will hold any charge. |
| B) | A will hold more charge in comparison to that of B. |
| C) | A will hold less charge in comparison to that of B. |
| D) | Both of the spheres will hold the same charge |
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