Three capacitors having capacitances `20muF, 30muF` and `40muF` are conneceted in series with a 12V battary. Find the charge on each of the capacitors. How much work has been done by the battery in charging the capacitors?

Explanation

The equivalent capacitance, when they are connected in series
`1 / C_eq = 1 / C_1 + 1 / C_2+ 1 / C_3`
`= 1 /20 + 1 / 30 + 1 / 40`
`C_eq = 9.23 mu F. (a)Let the equivalent charge at the
capacitor = q
In the series capacitor , charge on each capacitor is same as the equivalent
`q = cV = 9.23 xx 12 `
`=110 mu C on each`
Let the work done by the battery = W
` W = vq `
`= 12 xx 110 xx 10^(-6) `
` = 1.33 xx 10^(-3) J` .