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NEET 2001 (AIPMT) · Self-Inductance & Energy

Self-Inductance & Energy question from NEET 2001 (AIPMT)

Q83NEET 2001 · AIPMTMedium

Self-Inductance & Energy

For a coil having L = 2 mH, current flow through it is I=t2e−tI = t^2 e^{-t} then, the time at which emf become zero

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Answer: (a)

  1. e=−L dIdte = -L\,\dfrac{dI}{dt}, so e=0e = 0 when dIdt=0\dfrac{dI}{dt} = 0.
  2. dIdt=2te−t−t2e−t=te−t(2−t)\dfrac{dI}{dt} = 2te^{-t} - t^2e^{-t} = te^{-t}(2-t)
  3. dIdt=0⇒t=2 s\dfrac{dI}{dt} = 0 \Rightarrow t = 2\text{ s} (for t>0t > 0)
  4. So the answer is (a) 2 sec.
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