Question

Two identical sphres, one positively charged and the other negativily charged are held d cm apart.If the magnitude of the charges on the two spheres are equal , find the electric potential at a point midway on the line joining the centres of the two spheres.

Answer 1

Let the two sphere be placed as shown in the dia-gram below. Let the midpoint of the line joining the centre of the two sphere be P. Let a positive charge q be brought from infinity and placed at the point P.Then let w be the work done in bringing the charge q from infinity to point P against the positively -charged body. As the two bodies are identical and point P is at the same distance from the two charged sphere -wJ of work is done in moving charge q from infinity to P against negatively-charged sphere. Hence, the total word done in `w-w = 0`

As the total work done is zero, the potential.
`V = w/q = 0/q = 0`
`:.` The potential at P is zero.