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NEET 2021 · Resonance, Bandwidth & Q Factor

Resonance, Bandwidth & Q Factor question from NEET 2021

Q98NEET 2021Medium

Resonance, Bandwidth & Q Factor

A series LCR circuit containing 5.0 H inductor, 80μ\muF capacitor and 40Ω\Omega resistor is connected to 230V variable frequency ac source. The angular frequencies of the source at which power transferred to the circuit is half the power at the resonant angular frequency are likely to be:

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Answer: (d)

  1. ω0=1LC=15×80×10−6=10.02=50 rad/s\omega_0 = \frac{1}{\sqrt{LC}} = \frac{1}{\sqrt{5\times80\times10^{-6}}} = \frac{1}{0.02} = 50\text{ rad/s}
  2. Half-power bandwidth Δω=RL=405=8 rad/s\Delta\omega = \frac{R}{L} = \frac{40}{5} = 8\text{ rad/s}
  3. Half-power frequencies ω0±Δω2=50±4\omega_0 \pm \frac{\Delta\omega}{2} = 50 \pm 4
  4. So the answer is (d) 46 rad/s and 54 rad/s.
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