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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 = 1 s .

Options

  1. A0.08 A
  2. B0 A
  3. C1.0 A
  4. D2.0 A

Correct answer

D. 2.0 A

Step-by-step solution

The growth of current in an LR circuit is given by the equation: I = I₀ (1 - e^ -t/ ) Given the steady-state current I₀ = 2.0 A and time constant = 40 ms = 0.04 s . Substituting t = 1 s into the equation: I = 2.0 (1 - e^ -1/0.04 ) I = 2.0 (1 - e⁻²⁵) Since e⁻²⁵ is negligibly small ( e⁻²⁵ 0 ), the current is: I 2.0 (1 - 0) = 2.0 A

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