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JEE Main20204 Sep 2020Evening ShiftPhysicsAlternating CurrentActual

A series L - R circuit is connected to a battery of emf V . If the circuit is switched on at t = 0 , then the time at which the energy stored in the inductor reaches 1 n times of its maximum value, is :

Options

  1. AL R ln n n - 1
  2. BL R ln n + 1 n - 1
  3. CL R ln n n + 1
  4. DL R ln n - 1 n

Correct answer

A. L R ln n n - 1

Step-by-step solution

Potential energy stored in inductor is given by U = 1 2 L 2 ∪ ∝ l 2 U U 0 = 1 I 0 2 1 n = 1 I 0 2 1 I 0 = 1 - e - RT / L = 1 n t = L R ln n n - 1

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