Four electric charges `+q, +q, -q` and `-q` are placed at the corners of a square of side 2L (see figure). The electric potential at point `A`, mid-way between the two charges `+q` and `+q`, is

Options

A. zero
B. `(1)/(4 pi epsilon_(0)) (2q)/(L) ( 1 + sqrt(5))`
C. `(1)/(4 pi epsilon_(0)) (2q)/(L) (1 + (1)/(sqrt(5)))`
D. `(1)/(4 pi epsilon_(0)) (2q)/(L) (1 - (1)/(sqrt(5)))`

Answer

4

Explanation

`V_(A) = (1)/(4 pi in_(0)) [ (q)/(L) xx 2 + (-q)/(sqrt(5) L) xx 2]`
`= (1)/(4 pi in_(0)) (2q)/(L) [ 1 - (1)/(sqrt(5))]`