Two thin wire rings each having a radius R are placed at a distance d apart with their axes coiciding. The charges on the two rings are `+q` and `-q`. The potential difference between the centres of the two rings is

Options

A. `(QR)/(4pi epsi_(0)d^(2))`
B. `(Q)/(2pi epsi_(0)) ((1)/(R )(1)/(sqrt(R^(2)+ d^(2))))`
C. `(Q)/(4pi epsi_(0)) ((1)/(R ) -(1)/(sqrt(R^(2) + d^(2))))`
D. 0

Answer

B

Explanation

`V_(1) = (Q)/(4pi epsi_(0)) ((1)/(R )- (1)/(sqrt(R^(2) + d^(2))))`
`V_(2) = (-Q)/(4pi epsi_(0)) ((1)/(R )- (1)/(sqrt(R^(2) + d^(2))))`
`Delta V = V_(1) - V_(2)`