Question

An LC oscillator has L = 60 mH and C = 4.0 μF. If the current is maximum at t = 0, what will be the first time when the capacitor has maximum charge? Express your answer in ms (milliseconds).

Answer 1

In the ideal LC osciilation circuit.

There is an oscilattion of energy betwwen capacitor and inductor.

When the current is maximum all the energy is stored in inductor E = 1/2xLI2

When the current is zero OR the charge on capacitor is amximum all the energy is stored in capacitor E = Q2/2C

Esentially , in ideal case we must have

1/2xLI2 = = Q2/2C

The angular frequency is given by = (1/LC)1/2

and time period for this is oscillatin is given by T = 2π/ = 2π(LC)1/2

which give frequecy = 1/T Hz = 1/ 2π(LC)1/2

Here we need to find the time

T = 2π(LC)1/2 given

L = 60 mH = 60x 10-3 H

C = 4 F = 4 x 10-6 F

=> T = 2π ( 60x 10-3 x 4 x 10-6 )1/2 = 2π (24)1/2 x 10-4 s = 2π (24)1/2 x 10-1​​​​​ ms = 3.078 ms

-=-=-=-=

Hope it helps!

Have a noce day!