# NEET Physics Alternating Current Questions Solved

BOARD

The figure shows a series LCR circuit with L = 5.0 H, C = 80 µF, R = 40 Ω connected to a variable frequency 240 V source. Calculate

(i) The angular frequency of the source which drives the circuit at resonance.

(ii) The current at the resonating frequency.

(iii)The rms potential drop across the capacitor at resonance.                                    3mark

(i) $\omega =\frac{1}{\sqrt{LC}}$                                                                                          1/2mark

$\frac{1}{\sqrt{5×80×{10}^{-6}}}=50radian/s$                                                               1/2mark

(ii) Current at resonance

${I}_{rms}=\frac{{V}_{rms}}{R}=\frac{240}{40}A=6A$                                                                      (1/2,1/2)mark

(iii) ${V}_{rms}$ across capacitor

1/2mark

$=\frac{6×{10}^{6}}{4×{10}^{3}}V=\frac{6000}{4}V=1500V$                                                        1/2mark

Difficulty Level:

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