The point charge q is within the cavity of an electrically neutral conducting shell whose outer surface has spherical shape. Find the potential V at a Point P lying outside the shell at a distance r from the center O of the outer sphere.

A negatively charge -q will be induced on the inner surface of . cavity and positive charge +q will be induced on the outer surface, which will be uniformly distributed. There will be no field or potential at point P due to inner charges +q and -q. Potential at P will only be due to outer +q charge. SoVP=14πε0qr