A circular ring of radius R, as in figure, is charged with a charge Q for half of its length and -Q for the other half. Imagine the ring on a plane. Calculate the eletric field at some point, P, located at some distance d from the center of the ring and along the axis perpendicular to the plane containing the ring and passing through the center, O, of the ring. +

A circular ring of radius R, as in figure, is charged with a charge Q for half of its length and -Q for the other half. Imagine the ring on a plane. Calculate the eletric field at some point, P, located at some distance d from the center of the ring and along the axis perpendicular to the plane containing the ring and passing through the center, O, of the ring. +