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

Answer

C

Explanation

`U_(system) = (1)/(4pi epsilon_(0)) ((q)(-2q))/(a) + (1)/(4pi epsilon_(0)) ((-2q)(q))/(a) + (1)/(4pi epsilon_(0)) ((q)(q))/(2a)`
`U_(system) = (7q^(2))/(8pi epsilon_(0)a)`