Physics Alternating Current PMDC Conceptual Practice
PMDC Verified Question 34 of 127
If both the frequency of the AC supply and the inductance of an inductor are doubled, the inductive reactance \(X_L\) will:
A
Be doubled
B
Be halved
C
Increase by four times
D
Remain unchanged
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Increase by four times
Concept:

Inductive reactance is directly proportional to both frequency and inductance.

Formula / Reaction:

$$X_L = 2\pi f L$$

Solution:

  • Let initial reactance be \(X_L = 2\pi f L\).


  • If \(f' = 2f\) and \(L' = 2L\):


  • \(X_L' = 2\pi (2f)(2L) = 4(2\pi f L) = 4 X_L\).


  • Therefore, inductive reactance increases by a factor of 4.


Why other options are incorrect:

  • Opt_A: Reactance doubles if only one parameter is doubled, not both.


  • Opt_B: Halving occurs if parameters are halved.


  • Opt_D: Reactance scales directly with the product of frequency and inductance.

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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