Assume a uniformly charged ring of radius R and charge Q produces an electric field Ering at a point P on its axis at distance x away from the centre of the ring as shown in the figure. Now the same charge Q is spread uniformly over the circular area the ring encloses, forming a flat disk of charge with the same radius as shown in the figure. How does the electric field E disk produce by the disk at P compare with the field produced by the ring at the same point?
