An `LC` circuit contains a `20 mH` inductor asn a `50 mu F` capacitor with initial change of `10 mC`. The resistance of the circuit is negligible. Let the instant the circuit is closed be `t = 0`.

Options

A. t = 0
B. t = 1.54 ms
C. t = .3 14ms
D. t = .6 28ms

Answer

B

Explanation

Frequency of LC oscillation
`f = (1)/(2 pi sqrt(LC))`
`:.` Time period (T) `= 2 pi sqrt(LC)`
At `t = (T)/(4)` energy stored is completely magnetic
`t = (2 pi sqrt(20 xx 10^(-3) xx 50 xx 10^(-6)))/(4) = 1.57 ms~~ 1.54 ` ms