Easy MCQ +4 / -1 PYQ · JEE Mains 2021

A 100$\Omega$ resistance, a 0.1 $\mu$F capacitor and an inductor are connected in series across a 250 V supply at variable frequency. Calculate the value of inductance of inductor at which resonance will occur. Given that the resonant frequency is 60 Hz.

  1. A 0.70 H
  2. B 70.3 mH
  3. C 7.03 $\times$ 10<sup>$-$5</sup> H
  4. D 70.3 H Correct answer

Solution

C = 0.1 $\mu$F = 10<sup>$-$7</sup> F<br><br>Resonant frequency = 60 Hz.<br><br>${\omega _0} = {1 \over {\sqrt {LC} }}$<br><br>$2\pi {f_0} = {1 \over {\sqrt {LC} }} \Rightarrow L = {1 \over {4{\pi ^2}f_0^2C}}$<br><br>by putting values $L \simeq 70.3$ Hz.

About this question

Subject: Physics · Chapter: Alternating Current · Topic: AC Circuits: R, L, C

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