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The magnetic field energy in an inductor changes from maximum value to minimum value in `5.0 ms` when connected to an AC source. The frequency of the source isA. `20HZ`B. `50HZ`C. `200HZ`D. `500HZ` |
Answer» Correct Answer - B `U = (1)/(2) Li^(2)` U is maximum when I is maximu `= i_(0)` U is minimum when `I =0` Time taken by current to change its value from `I = i_(0) to I = 0 is T//4` `(T)/(4) = 5 xx 10^(-3) implies T = 0.02 sec` `f = (1)/(T) = (1)/(0.02) =50` Hz . |
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