Part5 — Electrical Engineering Interview Questions & Answers (MCQs)
Q.1 What is the formula for Power Factor? (P=Real Power, Q=Reactive Power, S=Apparent Power)
(a) Q/S
(b) P/S
(c) P/Q
Correct Answer: (b) P/S (✓)
Explanation: Watch the video for explanation
Q.2 What is the Unit of Power Factor?
(a) Watts
(b) Voltage-Amperes
(c)None
Correct Answer: (c)None ✔
Explanation: Watch the video for explanation
Q.3 What is the value of the Power Factor when θ = 45°?
(a) 1
(b) 0.707
(c) 0
Correct Answer: (b) 0.707 ✔
Explanation: Watch the video for explanation
Q.4 If we have a lagging Power Factor of 0.3, then which type of load is greater in the circuit?
(a) Capacitive Load
(b) Inductive Load
(c) Resistive Load
Correct Answer: Inductive Load ✔
Explanation: Watch the video for explanation
Q.5 What is the value of the Power Factor when we have a purely resistive load?
(a) 0
(b) 0.5
(c) 1
Correct Answer: © 1 ✔
Explanation: Watch the video for explanation
Q.6 Why is the P.F =1 for a purely resistive load?
(a) Only reactive power is consumed
(b) Only active power is consumed
© Both a & b
Correct Answer: (b) Only active power is consumed✔
Explanation: Watch the video for explanation
Q.7 What is a typical formula for Reactive Power? (Reactive Power=Q)
Hint: draw the power triangle
(a) Q=VI Cosθ
(b) Q=VI Sinθ
© Q=VI
Correct Answer: (b) Q=VI Sinθ ✔
Explanation: Watch the video for explanation
Q.8 What will be the angle between Real and Reactive Power when we have a purely inductive load?
(a) 0°
(b) 60°
© 90°
Correct Answer: © 90° ✔
Explanation: Watch the video for explanation
Q.9 An electric current of 5A is passing through an inductive load that has a potential difference of 4KV and a lagging power factor of 0.5. What will be its apparent power at load?
(a) 25 KVA
(b) 20 KVA
© 10 KVA
Correct Answer: 20 KVA ✔
Explanation: Watch the video for explanation
Q.10 When we have a load of leading Power Factor, then what will be the sign of reactive power?
(a) Positive
(b) Negative
Correct Answer: (b) Negative ✔
Explanation: Watch the video for explanation
Q.11 If we increase reactive power by increasing inductive load, then what effect will occur in apparent power, current, angle, and power factor due to an increase in reactive power? (θ=Angle, I=Current, S=Apparent Power, ↑=Increase, ↓=Decrease).
Hint: draw the power triangle and then compare
(a) S↑, θ↑, I↑, P.F↑
(b) S↑, θ↑, I↑, P.F↓
© S↑, θ↓, I↑, P.F↑
Correct Answer: (b) S↑, θ↑, I↑, P.F↓ ✔
Explanation: Watch the video for explanation
Q.12 Why is it important to have a Power Factor close to unity?
Hint: Unity Power Factor = 1
(a) A unity power factor will increase system losses and increases the current which reduces the power demand.
(b) A Unity Power factor will decrease system losses and decrease the current which reduces the power demand
© Low P.F decrease copper loses
Correct Answer: (b) A Unity Power factor will decrease system losses and decrease the current which reduces the power demand ✔
Explanation: No Explanation
Q.13 How Capacitor will improve the power factor in inductive loads?
(a) By connecting capacitor in parallel which reduces reactive power
(b) By connecting capacitor in series which reduces reactive power
© Both a & b
Correct Answer: (a) By connecting capacitor in parallel which reduces reactive power ✔
Explanation: Watch the video for explanation
Q.14 How do synchronous motors improve the power factor?
(a) At full load, the motor starts to provide reactive power because of the increase in magnetizing current which acts as an inductor.
(b) At No Load, the motor starts to provide reactive power because of the increase in magnetizing current which acts as a capacitor.
© None of these
Correct Answer:(b) At No Load, the motor starts to provide reactive power because of the increase in magnetizing current which acts as a capacitor. ✔
Explanation: Watch the video for explanation
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Q.15 What is the formula for finding capacitance in a circuit?
(a) 1/(2πfXC )
(b) 2πfXC
© 1/2πfC
Correct Answer: (a) 1/(2πfXC ) ✔
Explanation: No Explanation
Q.16 How much Power Factor is recommended for maximum efficiency and minimum power losses?
(a) ≤0.5
(b) ≥0.8
© >1.2
Correct Answer: (b) ≥0.8 ✔
Explanation: No Explanation
Q.17 If Q꜀> Qₗ then what will be the sign of the angle between Real and apparent power? (Q꜀=Reactive Power by capacitor, Qₗ=Reactive Power by Inductor)
(a) Negative
(b) Positive
Correct Answer: (a) Negative ✔
Explanation: No Explanation
Q.18 When Q꜀> Qₗ is the current lagging or is the voltage lagging? (Q꜀=Reactive Power by capacitor, Qₗ=Reactive Power by Inductor)
(a) Current lagging
(b) Voltage lagging
Correct Answer: (b) Voltage lagging ✔
Explanation: No Explanation
