Electro Magnetic Induction And Alternating Currents Question 189

Question: The current in an L-R circuit builds up to (3/4)th of its steady state value in 4 seconds. The time constant of this circuit is

Options:

A) 1ln2sec

B) 2ln2sec

C) 3ln2sec

D) 4ln2sec

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Answer:

Correct Answer: B

Solution:

  • I=I0(Iet/τ)

    where τ time constant

    34I0=I0(1et/τ)34=let/τ

    et/τ=14 ,,tτ

    In e=In,144τ=2

    In 2τ=2In,2



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