Calculate potential on the axis of a disc of radius R due to a charge Q uniformly distributed on its surface.
In the above figure, we can see that the disc is divided into several charged rings. Let P be the point on the axis of the disc at a distance x from the centre of the disc.
The radius of the ring is r and the width is dr. dq is the charge on the ring which is given as
The potential is given as
The total potential at P is given as