Two point charges `-q` and `+q` are located at points `(0,0-a)` and `(0,0,a)` respectively. The electric potential at point `(0,0,z)`is `(Z gt a)`

Options

A. `(qa)/(4piepsilon_0z^2)`
B. `(q)/(4piepsilon_0z^2)`
C. `(2qa)/(4piepsilon_0(z^2-a^2))`
D. `(2qa)/(4piepsilon_0(z^2+a^2))`

Answer

C

Explanation

`V_P=K[(-q)/((z+a))+(q)/((z-a))]=Kq [(-z+a+z+a)/(z^2-a^2)]`
`= (2qa)/(4pi epsilon_0 (z^2 -a^2))`