Physics Alternating Current PMDC Conceptual Practice
PMDC Verified Question 61 of 127
If the inductance of an inductor is doubled and the frequency of the AC supply is halved, the inductive reactance \(X_L\) will:
A
Remain unchanged
B
Double
C
Quadruple
D
Be halved
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Remain unchanged
Concept:

Inductive reactance is directly proportional to the product of frequency and inductance: \(X_L = 2\pi f L\).

Formula / Reaction:

$$X_L' = 2\pi (f/2) (2L) = 2\pi f L = X_L$$

Solution:

  • Halving frequency reduces reactance by half; doubling inductance increases reactance by two.


  • These two changes cancel each other out, leaving \(X_L\) unchanged.


Why other options are incorrect:

  • Opt_B, Opt_C, Opt_D: Incorrect because the factor of \(1/2\) and factor of \(2\) product to \(1\).

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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