Practice portal › Alternating Current › Resonance in Series LCR

For an A.C. L-C-R series circuit at the resonant frequency, which of the following is wrong?

Asked in GUJCET 2016 · Resonance condition and tuning

Answer: (3) Value of resistance is zero

Step-by-step solution

At resonance X_L=X_C, that is ω₀L=1/(ω₀C), so statement B holds.

The voltages across L and C are then equal and opposite, so their phase effects cancel: statement A holds.

Z=R+j(X_L-X_C)=R, a purely real impedance: statement D holds.

The resistance R belongs to the resistor and does not change with frequency. At resonance the impedance falls to R; the resistance does not fall to zero.

So the wrong statement is that the value of resistance is zero.

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