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Concepts Of Physics MCQ Edition [Volume 2]PhysicsElectromagnetic Induction

An LR circuit has a time constant of 40 ms . The circuit is connected at t = 0 and the steady-state current is found to be 2.0 A . Determine the current at t = 100 ms .

Options

  1. A0.92 A
  2. B1.8 A
  3. C0.66 A
  4. D0.16 A

Correct answer

B. 1.8 A

Step-by-step solution

The equation for the growth of current in an LR circuit is given by I(t) = I₀ (1 - e^ -t/ ) Substituting the given values I₀ = 2.0 A , t = 100 ms , and = 40 ms : I = 2.0 (1 - e^ -100/40 ) I = 2.0 (1 - e^ -2.5 ) Using the value e^ -2.5 0.082 : I = 2.0 (1 - 0.082) I = 2.0 0.918 = 1.836 A Rounding to appropriate significant figures, I 1.8 A .

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