### 100+ Capacitance and Capacitors Questions (Part 1)

1. What is the relation between current and voltage in a capacitor?
a) I=1/C*integral(Vdt)
b) I=CdV/dt
c) I=1/CdV/dt
d) I=Ct

2. If 2V is supplied to a 3F capacitor, calculate the charge stored in the capacitor.
a) 1.5C
b) 6C
c) 2C
d) 3C

3. Calculate the current in the capacitor having 2V supply voltage and 3F capacitance in 2seconds.
a) 2A
b) 5A
c) 6A
d) 3A

4. A 4microF capacitor is charged to 120V, the charge in the capacitor would be?
a) 480C
b) 480microC
c) 30C
d) 30microC

5. For high frequencies, capacitor acts as _________
a) Open circuit
b) Short circuit
c) Amplifier
d) Rectifier

6. For very low frequencies, capacitor acts as ________
a) Open circuit
b) Short circuit
c) Amplifier
d) Rectifier

7. A capacitor consists of_________
a) Two conductors
b) Two semiconductors
c) Two dielectrics
d) Two insulators

8. Capacitor preferred when there is high frequency in the circuits is __________
a) Electrolyte capacitor
b) Mica capacitor
c) Air capacitor
d) Glass capacitor

9. Capacitance increases with ________
a) Increase in plate area
b) Decrease in plate area
c) Increase in distance between the plates
d) Increase in density of the material

10. Capacitance increases with __________
a) Increase in distance between the plates
b) Decrease in plate area
c) Decrease in distance between the plates
d) Increase in density of the material

11. Which among the following expressions relate charge, voltage and capacitance of a capacitor?
a) Q=C/V
b) Q=V/C
c) Q=CV
d) C=Q2V

12. If a 2F capacitor has 1C charge, calculate the voltage across its terminals.
a) 0.5V
b) 2V
c) 1.5V
d) 1V

13. What is the voltage across a capacitor at the time of switching, that is, when t=0?
a) Infinity
b) 0V
c) Cannot be determined
d) 1V

14. What is the voltage across the capacitor if the switch is closed and steady state is reached?

a) 8V
b) 0V
c) 10V
d) Infinity

15. If one plate of a parallel plate capacitor is charged to positive charge the other plate is charged to?
a) Positive
b) Negative
c) Positive or negative
d) Not charged

16. When the voltage across a capacitor increases, what happens to the charge stored in it?
a) Increases
b) Decreases
c) Becomes zero
d) Cannot be determined

17. When will capacitor fully charged?
a) When the voltage across its plates is half the voltage from ground to one of its plates
b) When the current through the capacitor is a 1/root2 time its value
c) When the supply voltage is equal to the capacitor voltage
d) Never

18. What happens to the current flow in a fully charged capacitor?
a) Current flow stops
b) Current flow doubles
c) Current flow becomes half its original value
d) Current flow becomes one-fourth its original value

19. Calculate the capacitance of a capacitor that stores 40microC of charge and has a voltage of 2V.
a) 20F
b) 20microF
c) 10F
d) 10microF

20. What happens to the capacitance when the voltage across the capacitor increases?
a) Decreases
b) Increases
c) Becomes 0
d) No effect

21. A power factor of a circuit can be improved by placing which, among the following, in a circuit?
a) Inductor
b) Capacitor
c) Resistor
d) Switch

22. When the supply frequency increases, what happens to the capacitive reactance in the circuit?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero

23. Calculate the time constant of a series RC circuit consisting of a 100microF capacitor in series with a 100ohm resistor.
a) 0.1 sec
b) 0.1 msec
c) 0.01 sec
d) 0.01 msec

24. Capacitors charge and discharge in __________ manner.
a) Linear
b) Constant
c) Square
d) Exponential

25. Air has a dielectric constant of ___________
a) Unity
b) Zero
c) Infinity
d) Hundred

26. What is the value of capacitance of a capacitor which has a voltage of 4V and ha 8C of charge?
a) 2F
b) 4F
c) 6F
d) 8F

27. Unit of capacitance is___________
a) Volts
c) Henry
d) Newton

28. What will happen to the capacitor just after the source is removed?
a) It will not remain in its charged state
b) It will remain in its charged state
c) It will start discharging
d) It will become zero

29. Which among the following equations is incorrect?
a) Q=CV
b) Q=C/V
c) V=Q/C
d) C=Q/V

30. Capacitance is directly proportional to__________
a) Area of cross section between the plates
b) Distance of separation between the plates
c) Both area and distance
d) Neither area nor distance

31. What is the total capacitance when three capacitors, C1, C2 and C3 are connected in parallel?
a) C1/(C2+C3)
b) C1+C2+C3
c) C2/(C1+C3)
d) 1/C1+1/C2+1/C3

32. Calculate the total capacitance.

a) 10F
b) 15F
c) 13F
d) 20F

33. Calculate the voltage across AB if the total charge stored in the combination is 13C.

a) 1V
b) 2V
c) 3V
d) 4V

34. Calculate the charge in the 2F capacitor.

a) 200C
b) 100C
c) 300C
d) 400C

35. Calculate the charge in the 1F capacitor.

a) 200C
b) 100C
c) 300C
d) 400C

36. Calculate the total charge of the system.

a) 200C
b) 100C
c) 300C
d) 400C

37. When capacitors are connected in parallel, the total capacitance is always __________ the individual capacitance values.
a) Greater than
b) Less than
c) Equal to
d) Cannot be determined

38. When capacitors are connected in parallel, what happens to the effective plate area?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero

39. Three capacitors having a capacitance equal to 2F, 4F and 6F are connected in parallel. Calculate the effective parallel.
a) 10F
b) 11F
c) 12F
d) 13F

40. Two capacitors having capacitance value 4F, three capacitors having capacitance value 2F and 5 capacitors having capacitance value 1F are connected in parallel, calculate the equivalent capacitance.
a) 20F
b) 19F
c) 18F
d) 17F

41. What is the total capacitance when two capacitors C1 and C2 are connected in series?
a) (C1+C2)/C1C2
b) 1/C1+1/C2
c) C1C2/(C1+C2)
d) C1+C2

42. N capacitors having capacitance C are connected in series, calculate the equivalent capacitance.
a) C/N
b) C
c) CN
d) N/C

43. When capacitors are connected in series, the equivalent capacitance is ___________ each individual capacitance.
a) Greater than
b) Less then
c) Equal to
d) Insufficient data provided

44. What is the equivalent capacitance?

a) 1.5F
b) 0.667F
c) 2.45F
d) 2.75F

45. When capacitors are connected in series ___________ remains the same.
a) Voltage across each capacitor
b) Charge
c) Capacitance
d) Resistance

46. When capacitors are connected in series _______________ Varies
a) Voltage across each capacitor
b) Charge
c) Capacitance
d) Resistance

47. Four 10F capacitors are connected in series, calculate the equivalent capacitance.
a) 1.5F
b) 2.5F
c) 3.5F
d) 0.5F

48. Calculate the charge in the circuit.

a) 66.67C
b) 20.34C
c) 25.45C
d) 30.45C

49. Calculate the voltage across the 1F capacitor.

a) 33.33V
b) 66.67V
c) 56.56V
d) 23.43V

50. Calculate the voltage across the 2F capacitor.

a) 33.33V
b) 66.67V
c) 56.56V
d) 23.43V

51. The total voltage drop across a series of capacitors is __________
a) The voltage drop across any one of the capacitors
b) The sum of the voltage drop across each of the capacitors
c) The product of the voltage drop across each of the capacitors
d) Zero

52. Capacitors C1, C2 and C3 have voltage drops 2V, 3V and 5V respectively. Calculate the total voltage in the circuit.
a) 10V
b) 2V
c) 5V
d) 0V

53. What is the voltage across the 2F capacitor?

a) 240V
b) 200V
c) 220V
d) 120V

54. What is the voltage across the 4F capacitor?

a) 120V
b) 60V
c) 100V
d) 220V

55. Calculate the voltage across the 6F capacitor.

a) 120V
b) 60V
c) 40V
d) 220V

56. When capacitors are connected in series, which of the following rules are applied?
a) Voltage divider
b) Current divider
c) Both voltage divider and current divider
d) Neither voltage divider nor current divider

57. A capacitor does not allow sudden changes in _________
a) Current
b) Voltage
c) Resistance
d) Inductance

58. Which of the following expressions is correct with respect to the voltage across capacitors in series?
a) V1/V2=C2/C1
b) V2/V1=C2/C1
c) V1*V2=C1*C2
d) V1/C1=V2/C2

59. Two 4F capacitors are connected in series, calculate the voltage across each if the total voltage is 20V.
a) 10V
b) 5V
c) 20V
d) 0V

60. Two capacitors having voltage 2F and 4F are connected in series. This combination is connected to a 100V supply, calculate the voltage across the 2F capacitor.
a) 66.67V
b) 33.33V
c) 100V
d) 0V

61. Capacitor is a device used to__________
a) store electrical energy
b) vary the resistance
c) store magnetic energy
d) dissipate energy

62. Capacitor stores which type of energy?
a) kinetic energy
b) vibrational energy
c) potential energy
d) heat energy

63. Capacitor blocks__________ after long time.
a) alternating current
b) direct current
c) both alternating and direct current
d) neither alternating nor direct current

64. Why does capacitor block dc signal at steady state?
a) due to high frequency of dc signal
b) due to zero frequency of dc signal
c) capacitor doesnot pass any current at steady state
d) due to zero frequency of dc signal

65. If a parallel plate capacitor of plate area 2m2 and plate separation 1m store the charge of 1.77*10-11 C. What is the voltage across the capacitor?
a) 1V
b) 2V
c) 3V
d) 4V

66. Which of the following is a passive device?
a) Transistor
b) Rectifier
c) Capacitor
d) Vaccuum Tubes

67. What is the value of capacitance of a capacitor which has a voltage of 4V and has 16C of charge?
a) 2F
b) 4F
c) 6F
d) 8F

68. For which medium capacitance is high?
a) Air
b) Mica
c) Water
d) Metal

69. The conventional direction of electric field is ________
a) Positive to negative
b) Negative to positive
c) No specific direction
d) Direction cannot be determined

70. Electric field originates at __________
a) Positive charge
b) Negative charge
c) Neither positive nor negative
d) Both positive and negative

71. Electric field terminates at ________
a) Positive charge
b) Negative charge
c) Neither positive nor negative
d) Both positive and negative

72. Which among the following statements is true with regard to electric field lines?
a) Electric field lines always intersect
b) Electric field lines may or may not intersect
c) Electric field lines can be seen
d) Electric field lines never intersect

73. Which, among the following, is the field where electric charge experiences a force?
a) Electric field
b) Magnetic field
c) Gravitational field
d) Electric, magnetic and gravitational field

74. A field that spreads outwards in all directions is __________
a) Linear
c) Weak
d) Strong

75. In uniform fields, all points have ________ field strength.
a) Zero
b) Same
c) Infinity
d) Different

76. Which, among the following is the correct expression for an electric field?
a) E=F/C
b) E=F*C
c) E=F/Q
d) E=F*Q

77. What happens when one material is rubbed against another?
a) The material becomes electrically neutral
b) The material becomes electrically charged
c) The material becomes negatively charged
d) The material becomes positively charged

78. The insulant between the two plates of a capacitor is called _______
a) Conductor
b) Semi-conductor
c) Dielectric
d) Superconductor

79. Gauss law is applicable for_________
a) Point charge
b) Sheet charge
c) Line charge
d) Point, sheet and line charge

80. “Total electric flux through any closed surface is equal to the charge enclosed by that surface divided by permittivity”. This is the statement for?
a) Gauss law
b) Lenz law
c) Coloumb’s law

81. Electric flux density is a function of_______
a) Volume
b) Charge
c) Current
d) Voltage

82. As charge increases, what happens to flux density?
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero

83. As area increases, what happens to electric flux density?
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero

84. Which, among the following, is the correct expression for electric flux density?
a) D=epsilon*E
b) D=epsilon/E
c) D2=epsilon*E
d) D=epsilon*E2

85. Strength of the electric field is ___________
a) Directly proportional to the force applied
b) Inversely proportional to the force applied
c) Directly proportional to the square of the force applied
d) Inversely proportional to the square of the force applied

86. The force applied to a conductor is 10N if the charge in the conductor is 5C, what is the electric field intensity?
a) 10V/m
b) 2V/m
c) 3V/m
d) 15V/m

87. What is the electric flux density in free space if the electric field intensity is 1V/m?
a) 7.76*10-12C/m2
b) 8.85*10-12C /m2
c) 1.23*10-12C /m2
d) 3.43*10-12C /m2

88. If the charge in a conductor is 16C and the area of cross section is 4m2. Calculate the electric flux density.
a) 64C/m2
b) 16C/m2
c) 4C/m2
d) 2C/m2

89. In order to obtain a high value for capacitance, the permittivity of the dielectric medium should be?
a) Low
b) High
c) Zero
d) Unity

90. Find the capacitance of a capacitor whose area of cross section of the plates is 4m2 and distance of separation between the plates is 2m. The capacitor is placed in vacuum.
a) 1.77*10-11F
b) 1.34*10-11F
c) 2.33*10-11F
d) 5.65*10-11F

91. What is relative permittivity?
a) Equal to the absolute permittivity
b) Ratio of actual permittivity to absolute permittivity
c) Ratio of absolute permittivity to actual permittivity
d) Equal to the actual permittivity

92. What happens to relative permittivity when actual permittivity decreases?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero

93. What is the relative permittivity when the actual permittivity is 4F/m?
a) 4.57*10-11
b) 4.57*1012
c) 4.57*1011
d) 4.57*10-12

94. What happens to absolute permittivity when relative permittivity increases?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero

95. Calculate the actual permittivity of a medium whose relative permittivity is 5.
a) 4.43*10-11F/m
b) 4.43*10-12F/m
c) 4.43*1011F/m
d) 4.43*1012F/m

96. What is the unit for relative permittivity?
a) F/m
b) Fm
c) F/m2
d) No unit

97. Which, among the following, will be unity in free space?
a) Absolute permittivity
b) Relative permittivity
c) Actual permittivity
d) Both absolute and relative permittivity

98. Which, among the following, do not have any unit?
a) Absolute permittivity
b) Relative permittivity
c) Actual permittivity
d) Both absolute and relative permittivity

99. Which is the correct expression for capacitance of a multi plate capacitor?
a) C=absolute permittivity*A/d
b) C=Actual permittivity*(n-1)*A/d
c) C=Actual permittivity*(n)*A/d
d) Actual permittivity*(n+1)*A/d

100. What happens to the capacitance of a multi plate capacitor when the area of cross section of the plate decreases?
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero

101. What happens to the capacitance of a multi plate capacitor when the distance of separation between the plate increases?
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero

102. What happens to the capacitance of a multi plate capacitor when the number of plates increases?
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero

103. Find the capacitance of a multi plate capacitor whose actual permittivity= 5F/m, n=3, A=4m2and d=2m.
a) 10F
b) 20F
c) 30F
d) 40F

104. Find the capacitance of a multi plate capacitor whose relative permittivity=5, n=3, A=4m2 and d=2m.
a) 1.77*10-10 F
b) 1.77*1010 F
c) 1.77*10-11 F
d) 1.77*1011 F

105. Find the number of plates in the multi plate capacitor having C=20F absolute permittivity=5F/m, A=4m2 and d=2m.
a) 1
b) 2
c) 3
d) 4

106. Calculate the distance between the plates of the capacitor having C=20F, actual permittivity = 5F/m n=3 and A=4m2.
a) 1m
b) 2m
c) 3m
d) 4m

107. Calculate the area of cross section of the multi plate capacitor having C=20F, actual permittivity=5F/m n=3 and d=2m.
a) 1m2
b) 2m2
c) 3m2
d) 4m2