A 60 pF capacitor is fully charged by a 20 V supply. It is then disconnected from the supply and is connected to another uncharged 60 pF capacitor in parallel. The electrostatic energy that is lost in this process by the time the charge is redistributed between them is ( in nJ)

Options

A. 30
B. 15
C. 12
D. 6

Explanation

Energy loss `= U_(i) - U_(f)`
`= (1)/(2) CV^(2) =-2 [ (1)/(2) C ((V)/(2))^(2)]`
=`(1)/(2) CV^(2)-(1)/(4) CV^(2)`
`= (CV^(2))/(4)`
`= (60xx10^(-12)xx(20)^(2))/(4)`
`= (60xx400)/(4) xx10^(-12)`
`= 6xx10^(-9) J 6 ` n j