Problem 3.140

A point charge \(q\) is located at the centre \(O\) of a spherical uncharged conducting layer provided with a small orifice (Fig. 3.32). The inside and outside radii of the layer are equal to \(a\) and \(b\) respectively. What amount of work has to be performed to slowly transfer the charge \(q\) from the point \(O\) through the orifice and into infinity?