A series circuit has

PHYSICS · Multi-part · CBSE · Physics · Alternating Current · Alternating Current

Problem

A series

LCR

circuit has

R = 30\,\Omega

L = 150\,\text{mH}

and

C = 80\,\mu\text{F}

. It is connected to an ac source of

120\,\text{V}

(rms) whose frequency can be varied. (i) Determine the resonant frequency of the circuit. (ii) Calculate the rms current at resonance. (iii) The supply frequency is now set to

1.25

times the resonant frequency. Calculate the rms current at this new frequency. (iv) Hence find the ratio of the current at resonance to the current at the higher frequency obtained in part (iii). (v) Explain briefly why this ratio is different from unity.

Related theory

Resonance in AC Circuits
AC Circuit Analysis
Series LCR circuit
AC applied to a series LCR circuit
Alternating Current

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