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A capacitor C is connected across a D.C. source. The reactance of the capacitor will be ______.

Asked in GUJCET 2018 · Behaviour of R, L and C separately

Answer: (4) Infinite

Step-by-step solution

Idea: capacitive reactance is X_C = 1/(ω C) = 1/(2π fC).

For a d.c. source the frequency is f = 0.

As f → 0, X_C = 1/(2π fC) → ∞.

Physically: after a brief charging current, no steady current flows through a capacitor on d.c.; it blocks d.c. completely, so its reactance is infinite.

Why the other options are wrong

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