Two equal charges `q` are placed at a distance of `2a` and a third charge `-2a` is placed at the midpoint. The potential energy of the system is

Options

A. `(q^(2))/(8 pi epsilon_(0) a)`
B. `(6q^(2))/(8 pi epsilon_(0) a)`
C. `-(7q^(2))/(8 pi epsilon_(0) a)`
D. `(9q^(2))/(8 pi epsilon_(0) a)`

Answer

3

Explanation

`U = (1)/(4 pi in_(0)) [ (q* -2q)/(a) + (q*q)/(2a) + (-q*q)/(a)]`
`= (1)/(4pi in_(0)) [-(7q^(2))/(2a)] = -(7q^(2))/(8 pi in_(0) a)`