1000 similar electrified rain drops merge together into one drop so that their total charge remains uncharged. How is the electric energy affected ?

Answer

100 times

Explanation

Let `q` be the charge on each drop of radius `r`. Energy before merger
`U_(1) = 1000 xx (q^(2))/(2C) = 10^(3) (q^(2))/(2C)`
On merger, `(4)/(3) pi R^(3) = 1000xx (4)/(3) pi r^(3), :. R = 10r`.
Capacity becomes 10 times.
Energy after merger `= U_(2) = ((1000 q)^(2))/(2 (10 C)) = 10^(5) (q^(2))/(2C)`
`:. U_(2)//U_(1) = 100`