Practice portal › Alternating Current › Resonance in Series LCR

A sine voltage having a maximum value of 283 V and frequency 50 Hz is applied to an LCR series connection where R=3 Ω, L=25.48 mH and C=796 μF. Then the impedance is ______ at the resonance condition.

Asked in GUJCET 2020 · Resonance condition and tuning

Answer: (1) 3 Ω

Step-by-step solution

Given: R=3 Ω, L=25.48 mH and C=796 μF.

Idea: at resonance X_L=X_C, so they cancel and Z=√R²+(X_L-X_C)²=R.

So at the resonance condition Z=R=3 Ω. The peak voltage is not needed.

Check: resonance occurs at f₀=1/(2π√LC)=1/(2π√25.48×10⁻³×796×10⁻⁶)≈35.4 Hz.

At the source's own 50 Hz the circuit is not at resonance: X_L=8 Ω, X_C=4 Ω and Z=5 Ω.

So the impedance at the resonance condition is 3 Ω.

Why the other options are wrong

More Resonance in Series LCR questionsAll Resonance in Series LCR questions →

Reading this solution needs no sign-in. You only sign in to practise against the clock and keep your progress.

Practise this with a timer