Alternating Current Ques 1

1. In a series resonant circuit, having $L, C$ and $R$ as its elements, the resonant current is $i$. The power dissipated in the circuit at resonance is

[2002]

(a) $\frac{i^2 \mathrm{R}}{\left(\omega \mathrm{L}-\frac{1}{\omega \mathrm{C}}\right)}$

(b) zero

(c) $i^2 \omega \mathrm{L}$

(d) $i^2 \mathrm{R}$

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Answer:

Correct Answer: 1.(d)

Solution: (d)

At resonance $L \omega=\frac{1}{C \omega}, \omega=\frac{1}{\sqrt{L C}}$

Current through circuit $i=\frac{E}{R}$

Power dissipated at Resonance $=i^2 R$