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Posted by on Sunday, July 24, 2011 at 6:37pm.

How long does it take for the current in an circuit with = 150Ω and = 65mH to reach half its final value?

  • Physics - , Sunday, July 24, 2011 at 6:51pm

    i = (V/L)[ 1 - e^(-R t/L) ]
    at t = 0, i = 0
    at t-->oo , i --> V/L
    so when is
    [ 1 - e^(-R t/L) ] equal to 1/2 ?
    when e^(-Rt/L) = 1/2
    ln e^(-Rt/L) = -Rt/L = - .693

    so when
    t = .693 (L/R)

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