MCQs on Single Phase and Three Phase AC Circuit

MCQs on Single Phase and Three Phase AC Circuit

Definition of Single Phase Vs. Three Phase AC


AC (Alternating Current) is basically an electricity which passes through the conductive wires to operate the load such as washing machine, fan, LED etc. In the single phase AC, two wires are used in which first wire is line/Phase and second one is neutral. In the three phase AC, four wires are used in which three wires have line/phase and one is neutral. All the three wires of 3-Phase AC is 120° out of phase. Three phase Ac can be connected in Star and Delta Connection. All the MCQs on Single Phase and Three Phase AC circuits are published according to the new study syllabus for academic year 2021-22.


Read More: Questions On Capacitors in Series and Parallel MCQs


The aim is to provide AC Circuits MCQs objective questions and answers to understand the concepts of Single Phase, Three Phase Electricity. If you are willing to learn the concepts of Basic Electronics MCQs multiple choice questions with answer then read all the questions and answers. You will be surely able to qualify for all kinds of Quiz / tests / Interviews after understanding the Introduction to Single Phase and 3-Phase. If you are a students, technician or teacher then you can learn the basic concept of AC circuits applications, principle and function.


Single Phase and Three Phase AC Circuits MCQs (Questions and Answers)


Q1. The pure resistive AC circuit is called _______ circuit.

  1. conductive
  2. capacitive
  3. inductive
  4. noninductive
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Answer:    d

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Q2. The power factor of a circuit consists of a resistor is unity.       True / False

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Answer:    True

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Q3. In the pure resistive circuit, the current and voltage are ______.

  1. in-phase
  2. out of phase
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Answer:    a

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Q4. In the pure inductive circuit, the current always 90º lag behind the voltage.           True / False

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Answer:    True

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Q5. The power factor of a pure inductive circuit is _________.

  1. infinity
  2. unity
  3. zero
  4. none is correct
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Answer:    c

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Q6. The frequency is directly proportional to the inductive reactance.                    True / False

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Answer:    True

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Q7. The capacitive reactance is ________ proportional to the frequency.

  1. directly
  2. indirectly
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Answer:    b

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Q8. The power factor of a pure capacitive circuit is zero.         True / False

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Answer:    True

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Read More: Types of Resistors MCQs Questions and Answers


Q9. In the pure capacitive circuit, the current always _______ behind the voltage.

  1. 180º leads
  2. 90º leads
  3. 90º lags
  4. 180º lags
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Answer:    b

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Q10. The power factor of a RL circuit is less than from unity.           True / False

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Answer:    True

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Q11. The ratio between resistance and impedance of an AC circuit is called _______.

  1. power factor
  2. admittance
  3. conductance
  4. none is correct
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Answer:    a

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Q12. The ratio between real and apparent power is called power factor.              True / False

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Answer:    True

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Q13. A part of current which is in-phase to the applied voltage is called ______.

  1. passive part
  2. active part
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Answer:    b

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Q14. The reading of watt meter in any AC circuit is called real power.           True / False

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Answer:    True

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Q15. The multiplication of voltage and current in any AC circuit is called ______ power.

  1. real
  2. apparent
  3. in-phase
  4. a & c are correct
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Answer:    b

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Read More: MCQs on Transformer Losses Questions and Answers


Q16. The magnitude of multiplication of apparent power with SinΦ is called Reactive.        True / False

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Answer:    True

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Q17. The opposite of admittance is ________.

  1. resistance
  2. conductance
  3. impedance
  4. inductance
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Answer:    c

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Q18. The component of an admittance which is in-phase to the applied voltage is called conductance.                                                                                                                                                       True / False

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Answer:    True

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Q19. The line losses from low power factor are _________.

  1. high
  2. low
  3. medium
  4. a & b are correct
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Answer:    a

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Q20. The performance of a system with low power factor becomes low.          True / False

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Answer:    True

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Q21. The voltage drops are _______ after increasing power factor. 

  1. increased
  2. decreased
  3. same
  4. none is correct
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Answer:    d

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Read More: MCQs on Amplifier Circuits Objective Questions


Q22. The power bill is decreased after increasing of power factor.          True / False

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Answer:    True

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Q23. A _______ component is used in the AC circuit to increase power factor.

  1. resistor
  2. inductor
  3. capacitor
  4. transistor
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Answer:    c

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Q24. In any circuit, the value of XC becomes equal to the value of XL then it is called Resonant circuit.                                                                                                                                                        True / False

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Answer:    True

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Q25. In the _______ resonant circuit, the resistance will be lowest and current will be highest.

  1. series
  2. parallel
  3. a & b both are correct
  4. none is correct
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Answer:    a

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Q26. The power factor of a circuit on resonance is unity.          True / False

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Answer:    True

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Q27. A system which includes more than one phases is called _______.

  1. poly phase
  2. three phase
  3. multi phase
  4. all are correct
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Answer:    a

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Q28. All the windings of three phase alternator are 120° from each other.          True / False

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Answer:    True

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Q29. The windings of two phase alternator are ______ from each other.

  1. 120°
  2. 180°
  3. 90°
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Answer:    c

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Q30. The voltage drops from source to load are minimum in three phase system.          True / False

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Answer:    True

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Q31. The high amount of power can be transmit with ______ phase system.

  1. poly
  2. multi
  3. single
  4. all are correct
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Answer:    a

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Q32. The sequence of phases is called phase sequence.          True / False

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Answer:    True

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Q33. The current will be ______ which is passing through the neutral wire, in case of balance load.

  1. maximum
  2. minimum
  3. zero
  4. infinity
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Answer:    c

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Q34. The voltages between line and neutral are called phase voltage.          True / False

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Answer:    True

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Q35. The voltages between two lines are called ______ voltages.

  1. phase
  2. neutral
  3. line
  4. all are correct
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Answer:    c

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Q36. The value of phase current and line current is equal in start connection.          True / False

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Answer:    True

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Q37. The value of line voltage and phase voltage is _______ in delta connection.

  1. equal
  2. maximum
  3. same
  4. zero
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Answer:    a

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Q38. The value of total power on balance load is same in star & delta connection.          True / False

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Answer:    True

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Q39. The line voltage is ________ of the phase voltage in star connection.

  1. 1.3x
  2. 2.9x
  3. 1.7x
  4. 0.9x
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Answer:    c

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Q40. A coil of watt meter, which have high resistance is called pressure coil.          True / False

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Answer:    True

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Q41. The current coil watt meter is always connected in ______.

  1. series
  2. parallel
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Answer:    a

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Q42. Copper is less used in three phase rather single phase system.          True / False

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Answer:    True

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Q43. How to calculate total power of a circuit in two watt meter method ?

  1. single watt meter
  2. two watt meter
  3. three watt meter
  4. none is correct
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Answer:    b

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Q44. The size of three-phase machine is smaller than single phase with stable output.          True / False

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Answer:    True

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Q45. The power consumed in the AC circuit is due to ________ component.

  1. capacitor
  2. inductor
  3. resistor
  4. all are correct
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Answer:    c

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Q46. On a very high frequency, the parallel RC circuit acts as a pure capacitive circuit.       True / False

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Answer:    True

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Q47. The unit of apparent power is ______.

  1. volt
  2. volt/meter
  3. volt/amp
  4. watt/meter
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Answer:    c

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Q48. The unit of admittance is siemens.       True / False

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Answer:    True

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Q49. In the series RLC circuit, if the value of XL increased from the value of XC the circuit acts as a __________ circuit.

  1. capacitive
  2. inductive
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Answer:    b

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Q50. The power gain of three phase load is √3VLILCosΦ.       True / False

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Answer:    True

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