Physics Alternating Current DUHS 2025
PMDC Verified Question 76 of 127
If frequency of AC is doubled, the inductive reactance will:
A
Remain same
B
Be halved
C
Be doubled
D
Become zero.
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Be doubled
Concept:

Inductive reactance is the opposition offered by an inductor to the flow of alternating current, and it is directly proportional to the frequency of the AC source.

Formula / Reaction:

$$X_L = 2\pi f L$$

Solution:

  • Inductive reactance is expressed by the relation \(X_L = 2\pi f L\).


  • For a given inductor of fixed inductance \(L\), \(X_L \propto f\).


  • When the AC frequency is doubled (\(f' = 2f\)), the inductive reactance doubles accordingly (\(X_L' = 2 X_L\)).


Why other options are incorrect:

Since \(X_L\) is directly proportional to frequency, doubling \(f\) doubles \(X_L\); it cannot remain constant, reduce by half, or become zero.

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