InterviewSolution
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InterviewSolution
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In charging singe loop R - C circuit, after how many time constant, kthe potential energy in the capacitor will be 25% of its maximum value. |
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Answer» The potential energy of the capacitor at time t is `U = (q^(2))/(2C)` where `q = C epsilon(1-e^(t//RC))` Then `U = (C epsilon)/(2) (1 - e^(-t//RC))^2` where `(C epsilon^(2))/(2) = U_(0)` Putting `U = (U_(0))/(4) = (C epsilon^(2))/(8)`, we have `(1- e^(-t//RC))^(2) = (1)/(4)` or `1=e^(-t//RC) = (1)/(2)` or `e^(-t//RC) = (1)/(2)` or `(t)/(RC) In e = - In 2 or tau = (t)/(RC) = ln2` |
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