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## Homework Statement

A ball of outer radius a and inner radius b is charged with charge [itex] Q_1 [/itex]. Inside the ball there is a point charge with charge [itex] Q_2 [/itex] located at radial distance c from the centre of the ball. c<b<a

Find the value of the electrostatic potential at the centre of the ball.

## Homework Equations

[tex] -\Delta V = \int \vec{E}\cdot d\vec{s} [/tex]

[tex] V(0) - V(\infty ) = \int _0^{\infty} E_r\cdot dr [/tex]

[tex]V(\infty )= 0 [/tex]

E inside a conductor is zero.

## The Attempt at a Solution

Since the electric field inside a conductor is zero, I conclude that only the electric field from the point charge, located at c, is relevant for the potential at zero radial distance. Hence:

[tex] V(0) = \frac{Q_2}{4\pi \epsilon _0 c} [/tex]

Am I correct?