Two thin wire rings each having a radius R are placed at a distance d apart with their axes coinciding. The charges on the two rings are \[+q\] and \[-q\]. The potential difference between the centres of the two rings is [AIEEE 2005]

\[\frac{Q}{4\pi {{\varepsilon }_{0}}}\,\left[ \frac{1}{R}-\frac{1}{\sqrt{{{R}^{2}}+{{d}^{2}}}} \right]\]

\[QR/4\pi {{\varepsilon }_{0}}{{d}^{2}}\]

\[\frac{Q}{2\pi {{\varepsilon }_{0}}}\left[ \frac{1}{R}-\frac{1}{\sqrt{{{R}^{2}}+{{d}^{2}}}} \right]\]

Two thin wire rings each having a radius R are placed at a distance

1.	Two thin wire rings each having a radius R are placed at a distance d apart with their axes coinciding. The charges on the two rings are \[+q\] and \[-q\]. The potential difference between the centres of the two rings is [AIEEE 2005]
A.	Zero
B.	\[\frac{Q}{4\pi {{\varepsilon }_{0}}}\,\left[ \frac{1}{R}-\frac{1}{\sqrt{{{R}^{2}}+{{d}^{2}}}} \right]\]
C.	\[QR/4\pi {{\varepsilon }_{0}}{{d}^{2}}\]
D.	\[\frac{Q}{2\pi {{\varepsilon }_{0}}}\left[ \frac{1}{R}-\frac{1}{\sqrt{{{R}^{2}}+{{d}^{2}}}} \right]\]
Answer» E.