McqMate
Chapters
| 1. |
The force between two charges is 120 N. If the distance between the charges is doubled, the force will be |
| A. | 60 N |
| B. | 30 N |
| C. | 40 N |
| D. | 15 N |
| Answer» B. 30 N | |
| 2. |
The electric field intensity at a point situated 4 metres from a point charge is 200 N/C. If the distance is reduced to 2 metres, the field intensity will be |
| A. | 400 N/C |
| B. | 600 N/C |
| C. | 800 N/C |
| D. | 1200 N/C |
| Answer» C. 800 N/C | |
| 3. |
The lines of force due to charged particles are |
| A. | always straight |
| B. | always curved |
| C. | sometimes curved |
| D. | none of the above |
| Answer» B. always curved | |
| 4. |
The electric field at a point situated at a distance d from straight charged conductor is |
| A. | proportional to d |
| B. | inversely proportional to d |
| C. | inversely proportional to d |
| D. | none of the above |
| Answer» B. inversely proportional to d | |
| 5. |
The direction of electric field due +0 positive charge is . |
| A. | away from the charge |
| B. | towards the charge |
| C. | both (a) and (6) |
| D. | none of the above |
| Answer» A. away from the charge | |
| 6. |
A field line and an equipotential surface are |
| A. | always parallel |
| B. | always at 90° |
| C. | inclined at any angle 0 |
| D. | none of the above |
| Answer» B. always at 90° | |
| 7. |
The ability of charged bodies to exert force on 6ne another is attributed to the existence of |
| A. | electrons |
| B. | protons |
| C. | neutrons |
| D. | electric field |
| Answer» D. electric field | |
| 8. |
If the sheet of a bakelite is inserted between the plates of an air capacitor, the capacitance will |
| A. | decrease |
| B. | increase |
| C. | remains unchanged |
| D. | become zero |
| Answer» B. increase | |
| 9. |
A capacitor stores 0.24 coulombs at 10 volts. Its capacitance is |
| A. | 0.024 F |
| B. | 0.12 F |
| C. | 0.6 F |
| D. | 0.8 F |
| Answer» A. 0.024 F | |
| 10. |
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 |
| Answer» B. high permittivity | |
| 11. |
The units of capacitance are |
| A. | volts/coulomb |
| B. | coulombs/volt |
| C. | ohms |
| D. | henry/Wb |
| Answer» B. coulombs/volt | |
| 12. |
If three 15 uF capacitors are connected in series, the net capacitance is |
| A. | 5 uF |
| B. | 30 uF |
| C. | 45 uF |
| D. | 50 uF |
| Answer» A. 5 uF | |
| 13. |
If three 10 uF capacitors are connected in parallel, the net cararitance is |
| A. | 20 uF |
| B. | 30 uE |
| C. | 40 uF |
| D. | 50 uF |
| Answer» B. 30 uE | |
| 14. |
A dielectric material must be |
| A. | resistor |
| B. | insulator |
| C. | good conductor |
| D. | semi conductor |
| Answer» B. insulator | |
| 15. |
An electrolytic capacitor can be used for |
| A. | D.C. only |
| B. | AC. only |
| C. | both D.C. as well as A.C. |
| D. | none |
| Answer» A. D.C. only | |
| 16. |
The capacitance of a capacitor is not affected by |
| A. | distance between plates |
| B. | area of plates |
| C. | thickness of plates |
| D. | all of the above |
| Answer» C. thickness of plates | |
| 17. |
Which of the following is not a vector ? |
| A. | Linear momentum |
| B. | Angular momentum |
| C. | Electric field |
| D. | Electric potential |
| Answer» B. Angular momentum | |
| 18. |
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. | voltage across the plates decreases |
| C. | charge on the capacitor decreases |
| D. | charge on the capacitor increases |
| Answer» B. voltage across the plates decreases | |
| 19. |
If A.C. voltage is applied to capacitive circuit, the alternating current can flow in the circuit because |
| A. | varying voltage produces the charg¬ing and dicharging currents |
| B. | of high peak value |
| C. | charging current can flow |
| D. | discharge current can flow |
| Answer» A. varying voltage produces the charg¬ing and dicharging currents | |
| 20. |
Voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater than air. What will be the value of dielectric constant ? |
| A. | 50 |
| B. | 100 |
| C. | 150 |
| D. | 200 |
| Answer» B. 100 | |
| 21. |
Which of the following statements is correct ? |
| A. | Air capacitors have a blackband to indicate the outside foil |
| B. | Electrolytic capacitor must be con¬nected in the correct polarity |
| C. | Ceramic capacitors must be con¬nected in the correct polarity |
| D. | Mica capacitors are available in capacitance value of 1 to 10 pF |
| Answer» B. Electrolytic capacitor must be con¬nected in the correct polarity | |
| 22. |
The dissipation factor of a good dielectric is of the order of |
| A. | 0.0002 |
| B. | 0.002 |
| C. | 0.02 |
| D. | 0.2 |
| Answer» A. 0.0002 | |
| 23. |
"The total electric flux through any closed surface surrounding charges is equal to the amount oflcharge enclosed". The above statement is associated with |
| A. | Coulomb's square law |
| B. | Gauss's law |
| C. | Maxwell's first law |
| D. | Maxwell's second law |
| Answer» B. Gauss's law | |
| 24. |
Three capacitors each of the capacity C are given. The resultant capacity 2/3 C can be obtained by using them |
| A. | all in series |
| B. | all in parallel |
| C. | two in parallel and third in series with this combination |
| D. | two in series and third in parallel across this combination |
| Answer» C. two in parallel and third in series with this combination | |
| 25. |
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 |
| Answer» D. Thickness of the plates | |
| 26. |
Which of the following statement is true ? |
| A. | The current in the discharging capacitor grows linearly |
| B. | The current in the dicharging capacitor grows exponentially |
| C. | The current in the discharging capacitor decays exponentially |
| D. | The current in the discharging capacitor decreases constantly |
| Answer» B. The current in the dicharging capacitor grows exponentially | |
| 27. |
Which of the following expression is correct for electric field strength ? |
| A. | E = D/E |
| B. | E = D2/t |
| C. | E = jtD |
| D. | E= nD2 |
| Answer» A. E = D/E | |
| 28. |
In a capacitor the electric charge is stored in |
| A. | metal plates |
| B. | dielectric |
| C. | both (a) and (6) |
| D. | none of the above |
| Answer» B. dielectric | |
| 29. |
Which of the following materials has the highest value of dielectric constant? |
| A. | Glass |
| B. | Vacuum |
| C. | Ceramics |
| D. | Oil |
| Answer» C. Ceramics | |
| 30. |
Which of the following capacitors will have the least variation ? |
| A. | Paper capacitor |
| B. | Ceramic capacitor |
| C. | Silver plated mica capacitor |
| D. | None of the above |
| Answer» C. Silver plated mica capacitor | |
| 31. |
Which of the following statements is incorrect ? |
| A. | The leakage resistance of ceramic capacitors is generally high |
| B. | The stored energy in a capacitor decreases with reduction in value of capacitance |
| C. | The stored energy in a capacitor increases with applied voltage |
| D. | A wire cable has distributed capacitance between the conductors |
| Answer» B. The stored energy in a capacitor decreases with reduction in value of capacitance | |
| 32. |
Which of the following capacitors has relatively shorter shelf life ? |
| A. | Mica capacitor |
| B. | Electrolytic capacitor |
| C. | Ceramic capacitor |
| D. | Paper capacitor |
| Answer» B. Electrolytic capacitor | |
| 33. |
The sparking between two electrical contacts can be reduced by inserting a |
| A. | capacitor in parallel with contacts |
| B. | capacitor in series with each contact |
| C. | resistance in line |
| D. | none of the above |
| Answer» A. capacitor in parallel with contacts | |
| 34. |
In the case of a lossy capacitor, its series equivalent resistance value will be |
| A. | small |
| B. | very small |
| C. | large |
| D. | zero |
| Answer» C. large | |
| 35. |
The power dissipated in a pure capacitor is |
| A. | zero |
| B. | proportional to applied voltage |
| C. | proportional to value of capacitance |
| D. | both (b) and (c) above |
| Answer» A. zero | |
| 36. |
In a capacitive circuit |
| A. | a steady value of applied voltage causes discharge |
| B. | an increase in applied voltage makes a capacitor charge |
| C. | decrease in applied voltage makes a capacitor charge |
| D. | none of the above |
| Answer» B. an increase in applied voltage makes a capacitor charge | |
| 37. |
When a dielectric slab is introduced in a parallel plate capacitor, the potential difference between plates will |
| A. | remain uncharged |
| B. | decrease |
| C. | increase |
| D. | become zero |
| Answer» B. decrease | |
| 38. |
Capacitance increases with |
| A. | increase in plate area and decrease in distance between the plates |
| B. | increase in plate area and distance between the plates |
| C. | decrease in plate area and value of applied voltage |
| D. | reduction in plate area and distance between the plates |
| Answer» A. increase in plate area and decrease in distance between the plates | |
| 39. |
A capacitor consists of |
| A. | two insulators separated by a con¬ductor |
| B. | two conductors separated by an in¬sulator |
| C. | two insulators only |
| D. | two conductors only |
| Answer» B. two conductors separated by an in¬sulator | |
| 40. |
A paper capacitor is usually available in the form of |
| A. | tubes |
| B. | rolled foil |
| C. | disc |
| D. | meshed plates |
| Answer» B. rolled foil | |
| 41. |
Air capacitors are generally available in the range |
| A. | 10 to 400 pF |
| B. | 1 to 20 pF |
| C. | 100 to 900 pF |
| D. | 20 to 100 pF |
| Answer» A. 10 to 400 pF | |
| 42. |
The unit of capacitance is |
| A. | henry |
| B. | ohm |
| C. | farad |
| D. | farad/m |
| Answer» C. farad | |
| 43. |
A capacitor charged to 200 V has 2000 (iC of charge. The value of capacitance will be |
| A. | 10 F |
| B. | 10 uF |
| C. | 100 nF |
| D. | 1000 uF |
| Answer» B. 10 uF | |
| 44. |
A capacitor in a circuit became hot and ultimately exploded due to wrong con¬nections, which type of capacitor it could be ? |
| A. | Paper capacitor |
| B. | Ceramic capacitor |
| C. | Electrolytic capacitor |
| D. | Any-of the above |
| Answer» C. Electrolytic capacitor | |
| 45. |
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. | CV2 |
| B. | C2V |
| C. | CV2 |
| D. | CV |
| Answer» A. CV2 | |
| 46. |
The absolute permittivity of free space is given by |
| A. | 8.854 x 1(T9 F/m) |
| B. | 8.854 x 1(T10 F/m) |
| C. | 8.854 x KT11 F/m |
| D. | 8.854 x 10"12 F/m |
| Answer» B. 8.854 x 1(T10 F/m) | |
| 47. |
The relative permittivity of free space is given by |
| A. | 1 |
| B. | 10 |
| C. | 100 |
| D. | 1000 |
| Answer» A. 1 | |
| 48. |
Electric field intensity is a quantity |
| A. | scalar |
| B. | vector |
| C. | both (a) and (6) |
| D. | none of the above |
| Answer» B. vector | |
| 49. |
When 4 volts e.m.f. is applied across a 1 farad capacitor, it will store energy of |
| A. | 2 joules |
| B. | 4 joules |
| C. | 6 joules |
| D. | 8 joules |
| Answer» D. 8 joules | |
| 50. |
The capacitor preferred for high frequency circuits is |
| A. | air capacitor |
| B. | mica capacitor |
| C. | electrolytic capacitor |
| D. | none of the above |
| Answer» B. mica capacitor | |
| 51. |
The capacity of capacitor bank used in power factor correction is expressed in terms of |
| A. | kW |
| B. | kVA |
| C. | kVAR |
| D. | volts |
| Answer» C. kVAR | |
| 52. |
While testing a capacitor with ohm-metre, if the capacitor shows charging, but the final resistance reading is appreciably less than normal, it can be concluded that the capacitor is |
| A. | short-circuited |
| B. | open circuited |
| C. | alright |
| D. | leaky |
| Answer» D. leaky | |
| 53. |
If a 6 (iF capacitor is charged to 200 V, the charge in coulombs will be |
| A. | 800 uC |
| B. | 900 uC |
| C. | 1200 uC |
| D. | 1600 uC |
| Answer» C. 1200 uC | |
| 54. |
Which capacitor will be physically smaller for the same ratings ? |
| A. | Ceramic capacitor |
| B. | Paper capacitor |
| C. | Both will be of equal size |
| D. | None of the above |
| Answer» A. Ceramic capacitor | |
| 55. |
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. | 50 pF |
| B. | 100 pF |
| C. | 150 pF |
| D. | 200 pF |
| Answer» B. 100 pF | |
| 56. |
A mica capacitor and a ceramic capacitor both have the same physical dimensions. Which will have more value of capacitance ? |
| A. | Ceramic capacitor |
| B. | Mica capacitor |
| C. | Both will have identical value of capacitance |
| D. | It depends on applied voltage |
| Answer» A. Ceramic capacitor | |
| 57. |
Which of the following material has least value of dielectric constant ? |
| A. | Ceramics |
| B. | Oil |
| C. | Glass |
| D. | Paper |
| Answer» B. Oil | |
| 58. |
Which of the following capacitors will have the least value of breakdown voltage ? |
| A. | Mica |
| B. | Paper |
| C. | Ceramic |
| D. | Electrolytic |
| Answer» D. Electrolytic | |
| 59. |
Dielectric constant for mica is nearly |
| A. | 200 |
| B. | 100 |
| C. | 3 to 8 |
| D. | 1 to 2 |
| Answer» C. 3 to 8 | |
| 60. |
The value of dielectric constant for vacuum is taken as |
| A. | zero |
| B. | 1 |
| C. | 4 |
| D. | 10 |
| Answer» B. 1 | |
| 61. |
Which of the following capacitors is marked for polarity ? |
| A. | Air |
| B. | Paper |
| C. | Mica |
| D. | Electrolytic |
| Answer» D. Electrolytic | |
| 62. |
Which of the following capacitors can be used for temperature compensation ? |
| A. | Air capacitor |
| B. | Ceramic capacitor |
| C. | Paper capacitor |
| D. | None of the above |
| Answer» B. Ceramic capacitor | |
| 63. |
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 six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pF |
| C. | Capacitors in series provide less capacitance but a higher voltage breakdown rating for the combina¬tion |
| D. | A capacitor can store charge be¬cause it has a dielectric between two conductors |
| Answer» B. A six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pF | |
| 64. |
Paper capacitors usually have a tolerance of |
| A. | ± 5% |
| B. | ± 10% |
| C. | ± 15% |
| D. | ± 20% |
| Answer» B. ± 10% | |
| 65. |
For closer tolerances which of the following capacitors is usually preferred ? |
| A. | Paper capacitor |
| B. | Mica capacitor |
| C. | Ceramic disc capacitor |
| D. | None of the above |
| Answer» B. Mica capacitor | |
| 66. |
The electrostatic force between two charges of one coulomb each and placed at a distance of 0.5 m will be |
| A. | 36 x 10fa |
| B. | 36 x 107 N |
| C. | 36 x 108 N |
| D. | 36 x 109 N |
| Answer» D. 36 x 109 N | |
| 67. |
The units of volume charge density are |
| A. | Coulomb/metre |
| B. | Coulomb/metre |
| C. | Coulomb/metre |
| D. | Coulomb/metre |
| Answer» C. Coulomb/metre | |
| 68. |
"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. | Gauss's law |
| B. | Kirchhoff s law |
| C. | Faraday's law |
| D. | Lenz's law |
| Answer» A. Gauss's law | |
| 69. |
Dielectric strength of mica is |
| A. | 10 to 20 kV/mm |
| B. | 30 to 50 kV/mm |
| C. | 50 to 200 kV/mm |
| D. | 300 to 500 kV/mm |
| Answer» C. 50 to 200 kV/mm | |
| 70. |
The dielectric constant (relative permittivity) of glass is given by |
| A. | 0.1 to 0.4 |
| B. | 0.5 to 1.0 |
| C. | 2.0 to 4.0 |
| D. | 5 to 100 |
| Answer» D. 5 to 100 | |
| 71. |
capacitors are mainly used for radio frequency tuning. |
| A. | Paper |
| B. | Air |
| C. | Mica |
| D. | Electrolytic |
| Answer» B. Air | |
| 72. |
capacitors can be used only for D.C. |
| A. | Air |
| B. | Paper |
| C. | Mica |
| D. | Electrolytic |
| Answer» D. Electrolytic | |
| 73. |
capacitors are used in transistor circuits. |
| A. | Ceramic |
| B. | Paper |
| C. | Air |
| D. | Electrolytic |
| Answer» A. Ceramic | |
| 74. |
capacitors are used for audio frequency and radio frequency coupling and tuning. |
| A. | Air |
| B. | Mica |
| C. | Plastic film |
| D. | Ceramic |
| Answer» B. Mica | |
| 75. |
The inverse of capacitance is called |
| A. | reluctance |
| B. | conductance |
| C. | susceptance |
| D. | elastance |
| Answer» D. elastance | |
| 76. |
When the dielectric is homogeneous,the potential gradient is |
| A. | uniform |
| B. | non-uniform |
| C. | zero |
| D. | any of the above |
| Answer» A. uniform | |
| 77. |
The potential gradient across the material of low permittivity is than across the material of high permittivity. |
| A. | smaller |
| B. | greater |
| C. | both (a) and (b) |
| D. | none of the above |
| Answer» B. greater | |
| 78. |
________field is associated with the capacitor. |
| A. | Electric |
| B. | Magnetic |
| C. | Both (a) and (b) |
| D. | None of the above |
| Answer» A. Electric | |
| 79. |
A capacitor having capacitance of 5 uF is charged to a potential difference of 10,000 V. The energy stored in the capacitor is |
| A. | 50 joules |
| B. | 150 joules |
| C. | 200 joules |
| D. | 250 joules |
| Answer» D. 250 joules | |
| 80. |
A single core cable used on 33000 V has conductor diameter 10 mm and the in¬ternal diameter of sheath 25 mm. The maximum electrostatic stress in the cable is |
| A. | 62 x 105 V/m |
| B. | 72 x 105 V/m |
| C. | 82 x 105 V/m |
| D. | 92 x 105 V/m |
| Answer» B. 72 x 105 V/m | |
| 81. |
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 |
| A. | 0.56 x 1015 m/s2 |
| B. | 1.5 x 1015 m/s2 |
| C. | 1.6 x 1015 m/s2 |
| D. | 1.76 x 1015 m/s2 |
| Answer» D. 1.76 x 1015 m/s2 | |
| 82. |
The total deficiency or excess of electrons in a body is known as |
| A. | current |
| B. | voltage |
| C. | potential gradient |
| D. | charge |
| Answer» D. charge | |
| 83. |
The relative permittivity has the following units |
| A. | F/m |
| B. | m/F |
| C. | Wb/m |
| D. | no units |
| Answer» C. Wb/m | |
| 84. |
The phenomenon of an uncharged body getting charged merely by the nearness of a charged body is known as |
| A. | pholoelectric effect |
| B. | chemical effect |
| C. | magnetic effect |
| D. | induction |
| Answer» D. induction | |
| 85. |
A unit tube of flux is known as tube |
| A. | Newton |
| B. | Faraday |
| C. | Michale |
| D. | None of the above |
| Answer» B. Faraday | |
| 86. |
The number of Faraday tubes of flux passing through a surface in an electric field is called |
| A. | electric flux |
| B. | electric flux density |
| C. | magnetic flux density |
| D. | electric charge density |
| Answer» A. electric flux | |
| 87. |
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 the above |
| Answer» C. Coulomb's laws | |
| 88. |
at a point may be defined as equal to the lines of force passing normally through a unit cross section at that point. |
| A. | Electric intensity |
| B. | Magnetic flux density |
| C. | Electric flux |
| D. | None of the above |
| Answer» A. Electric intensity | |
| 89. |
Electric intensity at any point in an electric field is equal to the at that point. |
| A. | electric flux |
| B. | magnetic flux density |
| C. | potential gradient |
| D. | none of the above |
| Answer» C. potential gradient | |
| 90. |
Electric displacement is a______quantity. |
| A. | scalar |
| B. | vector |
| C. | both of the above |
| D. | none of the above |
| Answer» B. vector | |
| 91. |
at a point is equal to the negative potential gradient at that point. |
| A. | Electric intensity |
| B. | Electric flux |
| C. | Magnetic flux |
| D. | Magnetic flux density |
| Answer» A. Electric intensity | |
| 92. |
The unit of dielectric strength is given by |
| A. | V/m |
| B. | V2/m |
| C. | m/V |
| D. | m/V2 |
| Answer» A. V/m | |
| 93. |
Dielectric strength ______ with increasing thickness |
| A. | increases |
| B. | decreases |
| C. | remains unaltered |
| D. | none of the above |
| Answer» B. decreases | |
| 94. |
The property of a capacitor to store electricity is called its |
| A. | capacitance |
| B. | charge |
| C. | energy |
| D. | none of the above |
| Answer» A. capacitance | |
| 95. |
is that property of a capacitor which delays any change of voltage across it. |
| A. | Inductance |
| B. | Capacitance |
| C. | Potential gradient |
| D. | None of the above |
| Answer» B. Capacitance | |
| 96. |
A capacitance of 100 fiF is connected in series with a resistance of 8000 £2. The time constant of the circuit is |
| A. | 0.2 s |
| B. | 0.4 s |
| C. | 0.6 s |
| D. | 0.8 s |
| Answer» D. 0.8 s | |
| 97. |
In a cable capacitor, voltage gradient ismaximum at the surface of the |
| A. | earth |
| B. | conduction |
| C. | sheath |
| D. | insulator |
| Answer» B. conduction | |
| 98. |
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. | 37, initial |
| B. | 63.2, initial |
| C. | 63.2, final |
| D. | 37, final |
| Answer» C. 63.2, final | |
| 99. |
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. | 37 |
| B. | 42 |
| C. | 63 |
| D. | 73 |
| Answer» A. 37 | |
| 100. |
A capacitor consists of two |
| A. | ceramic plates and one mica disc |
| B. | insulators separated by a dielectric |
| C. | silver-coated insulators |
| D. | conductors separated by an insulator |
| Answer» D. conductors separated by an insulator | |
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