Eight charged water drops, each with a radius of `1 mm` and a charge of `10^(10)C`, coalesce to from a single drop. The potential of the big drop is

Options

A. `3.6 V`
B. `36 V`
C. `360 V`
D. `3600 V`

Answer

D

Explanation

Volume is conserved.
`:. (4)/(3)pir^(3) = 8 xx (4)/(3)pi r^(3)` or `R^(3) = 2^(3)r^(3)` or `R = 2r`
`V = (1)/(4pi epsilon_(0)) (8q)/(2r) = (4 xx 9 xx 10^(9) xx 10^(-10))/(1 xx 10^(-3)) "volt"`
`= 3600 "volt"`