The power dissipated in a pure inductor in AC circuit is MCQ with Answer and Explanation

The power dissipated in a pure inductor in AC circuit is
A. Zero
B. I²R
C. V²/R
D. VI
Answer: Option A
Solution (By JKExamLibrary)
Phase difference 90°, power factor zero, average power zero.

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Practice More Physics Questions

Question #1
The frequency of a wave is 1 kHz. Its time period is
A. 1 s
B. 0.01 s
C. 1000 s
D. 0.001 s

Correct Answer: Option D


Explanation:
T = 1/f = 1/1000 = 0.001 s = 1 ms.

This question belongs to: Science Physics
Question #2
The Q factor of a resonant LCR circuit is measure of
A. Impedance
B. Selectivity
C. Reactance
D. Power factor

Correct Answer: Option B


Explanation:
Higher Q means sharper resonance, better selectivity.

This question belongs to: Science Physics
Question #3
A metal rod of length L at temperature T₀ is heated to temperature T. If α is the coefficient of linear expansion, the new length is:
A. L(1 + αT₀)
B. Lα(T - T₀)
C. L(1 + αT)
D. L[1 + α(T - T₀)]

Correct Answer: Option D


Explanation:
Linear expansion formula: ΔL = L₀αΔT, where ΔT = T - T₀. Thus new length L' = L₀ + ΔL = L₀[1 + α(T - T₀)]. Option A incorrectly uses absolute temperature T instead of temperature change. Option C gives only the change, not total length. Option D uses initial temperature incorrectly. Memory aid: 'Expansion depends on temperature change, not absolute value'. This standard formula application is common in thermal physics questions. Always identify initial length and temperature reference point to avoid sign errors.

This question belongs to: Science Physics