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The two thin coaxial rings, each of radius 'a' and having charges +Q and −Q respectively are separated by a distance of 's'. The potential difference between the centres of the two rings is:

1. (Q)/(2πε₀) [(1)/(a)+(1)/(√(s²+a²)) ]
2. (Q)/(4πε₀) [(1)/(a)+(1)/(√(s²+a²)) ]
3. (Q)/(4πε₀) [(1)/(a)-(1)/(√(s²+a²)) ]
4. (Q)/(2πε₀) [(1)/(a)-(1)/(√(s²+a²)) ]

Correct answer: (Q)/(2πε₀) [(1)/(a)-(1)/(√(s²+a²)) ]

Solution

The correct option accurately represents the potential difference derived from the electric fields created by the charged rings, taking into account their respective distances and the geometry involved. The positive charge contributes to the potential at one center while the negative charge affects the other, leading to the specific form of the equation.

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