A capacitor of capacitance `5muF` is cahrged to potential `20V` and isolated. Now, an uncharged capacitor is connected in parallel to it. If the charge distributes equally on these capacitors, find total energy stored in capacitors.

Explanation

Let `C` be unknow capacitance
`Q'_(1)=Q'_(2)impliesC_(1)V=C_(2)V`
`5V=CVimplies C=5 muF`
Common potential:
`V=(C_(1)V_(1)+C_(2)V_(2))/(C_(1)+C_(2))=(5xx20+5xx0)/(5+5)=10V`
Total energy stored in capacitors:
`U_(f)=(1)/(2)(C_(1)+C_(2))V^(2)=(1)/(2)(5+5)(10)^(2)xx10^(-6)J`
`=500x10^(-6)=500muJ`