If the frequency of an AC source connected to a pure capacitor is doubled, the capacitive reactance will ________.

Question

Question

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RRB JE EE 22 Apr 2025 Shift 2 CBT 2 Official Paper

Answer 1

Concept

The capacitive reactance XC for a series RC circuit is given by:

\(X_C={1\over 2\pi fC}\)

From the above expression, we found that the frequency is inversely proportional to the capacitive reactance.

Calculation

Given, f₂ = 2f₁

\({X_{C2}\over X_{C1}}={f_1\over f_2}\)

\({X_{C2}\over X_{C1}}={f_1\over 2f_1}\)

\({X_{C2}}={X_{C1}\over 2}\)

If the frequency of an AC source connected to a pure capacitor is doubled, the capacitive reactance will decrease by half.