100+ Questions on current theorems

1. Find the value of I1, I2 and I3.

a) -0.566A, 1.29A, -1.91A
b) -1.29A, -0.566A, 1.91A
c) 1.29A, -0.566A, -1.91A
d) 1.91A, 0.566A, 1.29A
Answer: c

2. Find the value of V, if the value of I3= 0A.

a) 1.739 V
b) 6.5 V
c) 4.5V
d)2.739V
Answer: a

3. Find the value of R if the power in the circuit is 1000W.

a) 10 ohm
b) 9 ohm
c) 8 ohm
d) 7 ohm
Answer: c

4. Find the current in the 4 ohm resistor.

a) 5A
b) 0A
c) 2.2A
d) 20A
Answer: b

5. Nodal analysis is generally used to determine______
a) Voltage
b) Current
c) Resistance
d) Power
Answer: a

6. Mesh analysis is generally used to determine_________
a) Voltage
b) Current
c) Resistance
d) Power
Answer: b

7. What is the current in the circuit?

a) 0A
b) 15A
c) 5A
d) 10A
Answer: a

8. Does the 15A source have any effect on the circuit?

a) Yes
b) No
c) Cannot be determined
d) Yes, only when the 10V source is removed
Answer: b

9. KVL is associated with____________
a) Mesh analysis
b) Nodal analysis
c) Both mesh and nodal
d) Neither mesh nor nodal
Answer: a

10. KCL is associated with_________
a) Mesh analysis
b) Nodal analysis
c) Both mesh and nodal
d) Neither mesh nor nodal
Answer: b

11. Find the value of the currents I1, I2 and I3 flowing clockwise in the first, second and third mesh respectively.

a) 1.54A, -0.189A, -1.195A
b) 2.34A, -3.53A, -2.23A
c) 4.33A, 0.55A, 6.02A
d) -1.18A, -1.17A, -1.16A
Answer: a

12. Find the value of the currents I1 and I2 flowing clockwise in the first and second mesh respectively.

a) 0.96A, 1.73A
b) 0.96A, -1.73A
c) -0.96A, 1.73A
d) -0.96A, -1.73A
Answer: b

13. Find the value of V if the current in the 3 ohm resistor=0.

a) 3.5V
b) 6.5V
c) 7.5V
d) 8.5V
Answer: c

14. Find the value of V1 if the current through the 1 ohm resistor=0A.

a) 83.33V
b) 78.89V
c) 87.87V
d) 33.33V
Answer: a

15. Calculate the mesh currents I1 and I2 flowing in the first and second meshes respectively.

a) 1.75A, 1.25A
b) 0.5A, 2.5A
c) 2.3A, 0.3A
d) 3.2A, 6.5A
Answer: a

16. I1 is the current flowing in the first mesh. I2 is the current flowing in the second mesh and I3 is the current flowing in the top mesh. If all three currents are flowing in the clockwise direction, find the value of I1, I2 and I3.

a) 7.67A, 10.67A, 2A
b) 10.67A, 7.67A, 2A
c) 7.67A, 8.67A, 2A
d) 3.67A, 6.67A, 2A
Answer: a

17. Calculate the mesh currents.

a) 7A, 6A, 6.22A
b) 2A, 1A, 0.57A
c) 3A, 4A, 5.88A
d) 6A, 7A, 8.99A
Answer: b

18. Mesh analysis employs the method of ___________
a) KVL
b) KCL
c) Both KVL and KCL
d) Neither KVL nor KCL
Answer: a

19. Mesh analysis is generally used to determine _________
a) Voltage
b) Current
c) Resistance
d) Power
Answer: b

20. Mesh analysis can be used for __________
a) Planar circuits
b) Non-planar circuits
c) Both planar and non-planar circuits
d) Neither planar nor non-planar circuits
Answer: a

21. Find the value of the node voltage V.

a) -60V
b) 60V
c) 40V
d) -40V
Answer: a

22. Calculate the node voltages V1 and V2.

a) 12V, 13V
b) 26.67V, 11.33V
c) 11.33V, 26.67V
d) 13V, 12V
Answer: c

23. Find the node voltage V.

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

24. Calculate the node voltages.

a) 30.77V, 7.52V, 18.82V
b) 32.34V, 7.87V, 8.78V
c) 34.34V, 8.99V, 8.67V
d) 45.44V, 6.67V, 7.77V
Answer: a

25. Find the value of V1 and V2.

a) 87.23V, 29.23V
b) 23.32V, 46.45V
c) 64.28V, 16.42V
d) 56.32V, 78, 87V
Answer: c

26. Nodal analysis is generally used to determine_______
a) Voltage
b) Current
c) Resistance
d) Power
Answer: a

27. If there are 10 nodes in a circuit, how many equations do we get?
a) 10
b) 9
c) 8
d) 7
Answer: b

28. Nodal analysis can be applied for________
a) Planar networks
b) Non-planar networks
c) Both planar and non-planar networks
d) Neither planar nor non-planar networks
Answer: c

29. How many nodes are taken as reference nodes in a nodal analysis?
a) 1
b) 2
c) 3
d) 4
Answer: a

30. In superposition theorem, when we consider the effect of one voltage source, all the other voltage sources are ____________
a) Shorted
b) Opened
c) Removed
d) Undisturbed
Answer: a

31. In superposition theorem, when we consider the effect of one current source, all the other voltage sources are ____________
a) Shorted
b) Opened
c) Removed
d) Undisturbed
Answer: a

32. In superposition theorem, when we consider the effect of one voltage source, all the other current sources are ____________
a) Shorted
b) Opened
c) Removed
d) Undisturbed
Answer: b

33. In superposition theorem, when we consider the effect of one current source, all the other current sources are ____________
a) Shorted
b) Opened
c) Removed
d) Undisturbed
Answer: b

34. Find the value of Vx due to the 16V source.

a) 4.2V
b) 3.2V
c) 2.3V
d) 6.3V
Answer: b

35. Find Vx due to the 3A source.

a) 56V
b) 78V
c) 38V
d) 48V
Answer: d

36. Find the value of Vx due to the 10V source.

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

37. Find the voltage due to the 15A source.

a) 0V
b) 2V
c) 4V
d) 6V
Answer: a

38. Superposition theorem is valid for _________
a) Linear systems
b) Non-linear systems
c) Both linear and non-linear systems
d) Neither linear nor non-linear systems
Answer: a

39. Superposition theorem does not work for ________
a) Current
b) Voltage
c) Power
d) Works for all: current, voltage and power
Answer: c

40. Calculate the Thevenin resistance across the terminal AB for the following circuit.

a) 4.34 ohm
b) 3.67 ohm
c) 3.43 ohm
d) 2.32 ohm
Answer: b

41. Calculate V_th for the given circuit.

a) 5.54V
b) 3.33V
c) 6.67V
d) 3.67V
Answer: c

42. Calculate the current across the 4 ohm resistor.

a) 0.86A
b) 1.23A
c) 2.22A
d) 0.67A
Answer: a

43. The Thevenin voltage is the__________
a) Open circuit voltage
b) Short circuit voltage
c) Open circuit and short circuit voltage
d) Neither open circuit nor short circuit voltage
Answer: a

44. Thevenin resistance is found by ________
a) Shorting all voltage sources
b) Opening all current sources
c) Shorting all voltage sources and opening all current sources
d) Opening all voltage sources and shorting all current sources
Answer: c

45. Thevenin’s theorem is true for __________
a) Linear networks
b) Non-Linear networks
c) Both linear networks and nonlinear networks
d) Neither linear networks nor non-linear networks
Answer: a

46. In Thevenin’s theorem Vth is __________
a) Sum of two voltage sources
b) A single voltage source
c) Infinite voltage sources
d) 0
Answer: b

47. Vth is found across the ____________ terminals of the network.
a) Input
b) Output
c) Neither input nor output
d) Either input or output
Answer: b

48. Which of the following is also known as the dual of Thevenin’s theorem?
a) Norton’s theorem
b) Superposition theorem
c) Maximum power transfer theorem
d) Millman’s theorem
Answer: a

49. Can we use Thevenin’s theorem on a circuit containing a BJT?
a) Yes
b) No
c) Depends on the BJT
d) Insufficient data provided
Answer: b

50. The Norton current is the_______
a) Short circuit current
b) Open circuit current
c) Open circuit and short circuit current
d) Neither open circuit nor short circuit current
Answer: a

51. Norton resistance is found by?
a) Shorting all voltage sources
b) Opening all current sources
c) Shorting all voltage sources and opening all current sources
d) Opening all voltage sources and shorting all current sources
Answer: c

52. Norton’s theorem is true for __________
a) Linear networks
b) Non-Linear networks
c) Both linear networks and nonlinear networks
d) Neither linear networks nor non-linear networks
Answer: a

53. In Norton’s theorem Isc is__________
a) Sum of two current sources
b) A single current source
c) Infinite current sources
d) 0
Answer: b

54. Isc is found across the ____________ terminals of the network.
a) Input
b) Output
c) Neither input nor output
d) Either input or output
Answer: b

55. Can we use Norton’s theorem on a circuit containing a BJT?
a) Yes
b) No
c) Depends on the BJT
d) Insufficient data provided
Answer: b

56. Calculate the Norton resistance for the following circuit if 5 ohm is the load resistance.

a) 10 ohm
b) 11 ohm
c) 12 ohm
d) 13 ohm
Answer: c

57. Calculate the short circuit current is the 5 ohm resistor is the load resistance.

a) 0.72A
b) 0.32A
c) 0.83A
d) 0.67A
Answer: a

58. Find the current in the 5 ohm resistance using Norton’s theorem.

a) 1A
b) 1.5A
c) 0.25A
d) 0.5A
Answer: d

59. Which of the following is also known as the dual of Norton’s theorem?
a) Thevenin’s theorem
b) Superposition theorem
c) Maximum power transfer theorem
d) Millman’s theorem
Answer: a

60. A voltage source connected in series with a resistor can be converted to a?
a) Current source in series with a resistor
b) Current source in parallel with a resistor
c) Voltage source in parallel with a resistor
d) Cannot be modified
Answer: b

61. Calculate the total current in the circuit.

a) 2.3mA
b) 4.3mA
c) 3.3mA
d) 1.3mA
Answer: c

62. Find the value of voltage once source transformation is applied to the circuit.

a) 10V
b) 30V
c) 50V
d) 70V
Answer: c

63. Once the circuit is transformed to a voltage source where will the resistance be connected?

a) In series with the voltage source
b) In parallel with the voltage source
c) The resistance is removed from the circuit
d) Resistance is multiplied by 10 and connected in series with the source
Answer: a

64. What will the value of the current be once source transformation is applied to the circuit?

a) 10A
b) 20A
c) 30A
d) 40A
Answer: a

65. Once the circuit is transformed into a current source where will the resistance be connected?

a) In series with the current source
b) In parallel with the current source
c) The resistance is removed from the circuit
d) Resistance is multiplied by 10 and connected in parallel with the source
Answer: b

66. A current source connected in parallel with a resistor can be converted to a?
a) Current source in series with a resistor
b) Voltage source in series with a resistor
c) Voltage source in parallel with a resistor
d) Cannot be modified
Answer: b

67. A source transformation is_________
a) Unilateral
b) Bilateral
c) Unique
d) Cannot be determined
Answer: b

68. In source transformation________
a) Voltage source remains the same
b) Current sources remain the same
c) Both voltage and current source remain the same
d) Resistances remain the same
Answer: d

69. If there are 3 10V sources connected in parallel then on source transformation__________
a) The effect of all the sources is considered
b) The effect of only one source is considered
c) The effect of none of the sources is considered
d) The effect of only 2 sources is considered.
Answer: b

70. The value of the 3 resistances when connected in star connection is_________

a) 2.32ohm,1.22ohm, 4.54ohm
b) 3.55ohm, 4.33ohm, 5.67ohm
c) 2.78ohm, 1.67ohm, 0.83ohm
d) 4.53ohm, 6.66ohm, 1.23ohm
Answer: c

71. Which, among the following is the right expression for converting from delta to star?
a) R1=Ra*Rb/(Ra+Rb+Rc), R2=Rb*Rc/(Ra+Rb+Rc), R3=Rc*Ra/(Ra+Rb+Rc)
b) R1=Ra/(Ra+Rb+Rc), R2=Rb/(Ra+Rb+Rc), Rc=/(Ra+Rb+Rc)
c) R1=Ra*Rb*Rc/(Ra+Rb+Rc), R2=Ra*Rb/(Ra+Rb+Rc), R3=Ra/(Ra+Rb+Rc)
d) R1=Ra*Rb*Rc/(Ra+Rb+Rc), R2=Ra*Rb*Rc/(Ra+Rb+Rc), R3=Ra*Rb*Rc/(Ra+Rb+Rc)
Answer: a

72. Find the equivalent star network.

a) 2.3ohm, 2.3ohm, 2.3ohm
b) 1.2ohm, 1.2ohm, 1.2ohm
c) 3.3ohm, 3.3ohm, 3.3ohm
d) 4.5ohm, 4.5ohm, 4.5ohm
Answer: b

73. Star connection is also known as__________
a) Y-connection
b) Mesh connection
c) Either Y-connection or mesh connection
d) Neither Y-connection nor mesh connection
Answer: a

74. Rab is the resistance between the terminals A and B, Rbc between B and C and Rca between C and A. These 3 resistors are connected in delta connection. After transforming to star, the resistance at A will be?
a) Rab*Rac/(Rab+Rbc+Rca)
b) Rab/(Rab+Rbc+Rca)
c) Rbc*Rac/(Rab+Rbc+Rca)
d) Rac/(Rab+Rbc+Rca)
Answer: a

75. Rab is the resistance between the terminals A and B, Rbc between B and C and Rca between C and A. These 3 resistors are connected in delta connection. After transforming to star, the resistance at B will be?
a) Rac/(Rab+Rbc+Rca)
b) Rab/(Rab+Rbc+Rca)
c) Rbc*Rab/(Rab+Rbc+Rca)
d) Rab/(Rab+Rbc+Rca)
Answer: c

76. Rab is the resistance between the terminals A and B, Rbc between B and C and Rca between C and A. These 3 resistors are connected in delta connection. After transforming to star, the resistance at C will be?
a) Rac/(Rab+Rbc+Rca)
b) Rab/(Rab+Rbc+Rca)
c) Rbc*Rac/(Rab+Rbc+Rca)
d) Rab/(Rab+Rbc+Rca)
Answer: c

77. Find the current in the circuit.

a) 0.54A
b) 0.65A
c) 0.67A
d) 0.87A
Answer: a

78. If a 6 ohm, 2ohm and 4ohm resistor is connected in delta, find the equivalent star connection.
a) 1ohm, 2ohm, 3ohm
b) 2ohm, 4ohm, 7ohm
c) 5ohm, 4ohm, 2ohm
d) 1ohm, 2ohm, 2/3ohm
Answer: d

79. If a 4ohm, 3ohm and 2ohm resistor is connected in delta, find the equivalent star connection.
a) 8/9ohm, 4/3ohm, 2/3ohm
b) 8/9ohm, 4/3ohm, 7/3ohm
c) 7/9ohm, 4/3ohm, 2/3ohm
d) 8/9ohm, 5/3ohm, 2/3ohm
Answer: a

80. Find the equivalent delta circuit.

a) 9.69 ohm, 35.71 ohm, 6.59 ohm
b) 10.69 ohm, 35.71 ohm, 6.59 ohm
c) 9.69 ohm, 34.71 ohm, 6.59 ohm
d) 10.69 ohm, 35.71 ohm, 7.59 ohm
Answer: a

81. Which, among the following is the correct expression for star-delta conversion?
a) R1=Ra*Rb/(Ra+Rb+Rc), R2=Rb*Rc/(Ra+Rb+Rc), R3=Rc*Ra/(Ra+Rb+Rc)b)
b) R1=Ra/(Ra+Rb+Rc), R2=Rb/(Ra+Rb+Rc), Rc=/(Ra+Rb+Rc)
c) R1=Ra+Rb+Ra*Rb/Rc, R2=Rc+Rb+Rc*Rb/Ra, R3=Ra+Rc+Ra*Rc/Rb
d) R1=Ra*Rb/Rc, R2=Rc*Rb/Ra, R3=Ra*Rc/Rb
Answer: c

82. Find the equivalent resistance between X and Y.

a) 3.33 ohm
b) 4.34 ohm
c) 5.65 ohm
d) 2.38 ohm
Answer: d

83. Delta connection is also known as____________
a) Y-connection
b) Mesh connection
c) Either Y-connection or mesh connection
d) Neither Y-connection nor mesh connection
Answer: b

84. Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between B and C?
a) Rc+Rb+Rc*Rb/Ra
b) Rc+Rb+Ra*Rb/Rc
c) Ra+Rb+Ra*Rc/Rb
d) Rc+Rb+Rc*Ra/Rb
Answer: a

85. Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between A and C?
a) Ra+Rb+Ra*Rb/Rc
b) Ra+Rc+Ra*Rc/Rb
c) Ra+Rb+Ra*Rc/Ra
d) Ra+Rc+Ra*Rb/Rc
Answer: b

86. Ra is resistance at A, Rb is resistance at B, Rc is resistance at C in star connection. After transforming to delta, what is resistance between A and B?
a) Rc+Rb+Ra*Rb/Rc
b) Ra+Rb+Ra*Rc/Rb
c) Ra+Rb+Ra*Rb/Rc
d) Ra+Rc+Ra*Rc/Rb
Answer: c

87. If a 1ohm 2ohm and 32/3ohm resistor is connected in star, find the equivalent delta connection.
a) 34 ohm, 18.67 ohm, 3.19 ohm
b) 33 ohm, 18.67 ohm, 3.19 ohm
c) 33 ohm, 19.67 ohm, 3.19 ohm
d) 34 ohm, 19.67 ohm, 3.19 ohm
Answer: a

88. If an 8/9ohm, 4/3ohm and 2/3ohm resistor is connected in star, find its delta equivalent.
a) 4ohm, 3ohm, 2ohm
b) 1ohm, 3ohm, 2ohm
c) 4ohm, 1ohm, 2ohm
d) 4ohm, 3ohm, 1ohm
Answer: a

89. Find the equivalent resistance between A and B.

a) 32ohm
b) 31ohm
c) 30ohm
d) 29ohm
Answer: d

90. The maximum power drawn from source depends on __________
a) Value of source resistance
b) Value of load resistance
c) Both source and load resistance
d) Neither source or load resistance
Answer: b

91. The maximum power is delivered to a circuit when source resistance is __________ load resistance.
a) Greater than
b) Equal to
c) Less than
d) Greater than or equal to
Answer: b

92. If source impedance is a complex number Z, then load impedance is equal to _________
a) Z’
b) -Z
c) -Z’
d) Z
Answer: a

93. If ZL=Zs’, then RL=?
a) -RL
b) Rs
c) -Rs
d) 0
Answer: b

94. Calculate the value of RL across A and B.

a) 3.45ohm
b) 2.91ohm
c) 6.34ohm
d) 1.54ohm
Answer: b

95. Calculate Eth.

a) 3.43V
b) 4.57V
c) 3.23V
d) 5.34V
Answer: b

96. Calculate the maximum power transferred.

a) 1.79W
b) 4.55W
c) 5.67W
d) 3.78W
Answer: a

97. Does maximum power transfer imply maximum efficiency?
a) Yes
b) No
c) Sometimes
d) Cannot be determined
Answer: b

98. Under the condition of maximum power efficiency is?
a) 100%
b) 0%
c) 30%
d) 50%
Answer: d

99. Name some devices where maximum power has to be transferred to the load rather than maximum efficiency.
a) Amplifiers
b) Communication circuits
c) Both amplifiers and communication circuits
d) Neither amplifiers nor communication circuits
Answer: c

100. In an AC circuit, resistance 50 Ω, inductance 0.3 H and capacitance 15 μF is connected to an AC voltage source 25 V, 50 Hz. Determine the inductive reactance in the circuit.
a) 36 ohm
b) 95 ohm
c) 125 ohm
d) 140 ohm
Answer: b

101. In an AC circuit, resistance 50 Ω, inductance 0.3 H and capacitance 15 μF is connected to an AC voltage source 25 V, 50 Hz. Determine the capacitive reactance in the circuit.
a) 316 ohm
b) 195 ohm
c) 124 ohm
d) 212 ohm
Answer: d

102. In an AC circuit, resistance 50 Ω, inductance 0.3 H and capacitance 15 μF is connected to an AC voltage source 25 V, 50 Hz. Determine the impedance in the circuit.
a) 110 ohm
b) 100 ohm
c) 125 ohm
d) 140 ohm
Answer: c

103. In an AC circuit, resistance 50 Ω, inductance 0.3 H and capacitance 15 μF is connected to an AC voltage source 25 V, 50 Hz. Determine the current in the circuit.
a) 0.01 A
b) 0.2 A
c) 0.02 A
d) 0.002 A
Answer: b

104. Find the value of the source current from the following circuit.

a) 2.54A
b) 6.67A
c) 3.35A
d) 7.65A
Answer: a

105. Find the value of the source voltage from the following circuit.

a) 49.2V
b) 34.6V
c) 65.2V
d) 25.6V
Answer: a

106. In an AC circuit, resistance 50 Ω, inductance 0.3 H and capacitance 15 μF is connected to an AC voltage source 25 V, 50 Hz. Determine the phase difference between current and voltage.
a) 670
b) 540
c) 470
d) 770
Answer: a

107. What value of direct current must flow through a resistor to produce the same heating power as an alternating current with a peak value of 3.5 A?
a) 1.5 A
b) 2.5 A
c) 3.5 A
d) 4.5 A
Answer: b

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