The circular plates A and B of a parallel plate air capacitor have a diameter of 0.1 m and are `2 xx 10^(-3) m` apart. The plates C and D of a similar capacitor have a diameter of `0.12 m` and are `3 xx 10^(-3)m` apart. Plate A is earthed. Plates B and D are connected together. Plate C is connected to the positive pole of a 120V battery whose negative is earthed. The energy stored in the system is

Answer

`(i) (30pi in_(0))/(49)~~17pF " " (ii) 122.4 nJ`