Physics Alternating Current PMDC Conceptual Practice
PMDC Verified Question 63 of 127
The instantaneous rate of energy consumption in a pure inductor across a complete AC cycle averages to:
A
\(V_0 I_0\)
B
\(I_{\text{rms}}^2 X_L\)
C
Zero
D
\(\frac{1}{2} L I_0^2\)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Zero
Concept:

In a pure inductor, the phase angle is \(\phi = 90^\circ\), which makes the power factor \(\cos(90^\circ) = 0\).

Formula / Reaction:

$$P_{\text{avg}} = V_{\text{rms}} I_{\text{rms}} \cos(90^\circ) = 0$$

Solution:

  • Energy alternates between the circuit and the inductor's magnetic field without thermal loss, giving zero average power dissipation.


Why other options are incorrect:

  • Opt_A: Peak power product.


  • Opt_B: Reactive power in VAR.


  • Opt_D: Maximum energy stored in magnetic field in Joules, not power in Watts.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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