Question

A series RLC circuit has R = 10 Ω, |XL| = 20 Ω and |XC| = 20 Ω is connected across an AC supply of 200 Vrms. The RMS voltage across the capacitor is ____________

(a) 200∠-90° V

(b) 200∠90° V

(c) 400∠90° V

(d) 400∠-90° V

Answer 1

Right choice is (d) 400∠-90° V

The explanation is: Q = (frac{|X_L|}{R} = frac{|X_C|}{R})

So, Q = (frac{20}{10}) = 2

Rms voltage across capacitor, VCrms = QV∠-90°

Or, VCrms = 2 X 200∠-90°

Or, VCrms = 400∠-90° V.