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NEET 2024 · LC Oscillations

LC Oscillations question from NEET 2024

Q11NEET 2024Medium

LC Oscillations

The amplitude of the charge oscillating in a circuit decreases exponentially as Q=Q0e−Rt/2LQ = Q_0 e^{-Rt/2L}, where Q0Q_0 is the charge at t=0 st = 0\text{ s}. The time at which charge amplitude decreases to 0.50Q00.50Q_0 is nearly: [Given that R=1.5 Ω, L=12 mH, ln⁡(2)=0.693R = 1.5\,\Omega,\ L = 12\text{ mH},\ \ln(2) = 0.693]

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Answer: (b)

  1. 0.5Q0=Q0e−Rt/2L⇒Rt2L=ln⁡20.5Q_0 = Q_0 e^{-Rt/2L} \Rightarrow \frac{Rt}{2L} = \ln 2
  2. t=2Lln⁡2R=2×12×10−3×0.6931.5t = \frac{2L\ln 2}{R} = \frac{2 \times 12\times10^{-3} \times 0.693}{1.5}
  3. t=1.109×10−2 st = 1.109\times10^{-2}\text{ s}
  4. So the answer is (b) 11.09 ms11.09\text{ ms}.
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