### 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**

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**

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**