Question

Total charge q2 is uniformly placed on a ring of radius R. The magnitude of the electric field at position z on the axis of the ring is given by ((kq2z)/(R^2+z^2)^(3/2))

A uniformly charged rod of total charge q1 and length L is now placed on the z axis. The nearest end of the rod is at distance L from the center of the ring, i.e. the rod extends from z = L to z = 2L (see figure on right).

Find an expression for the magnitude of the force exerted by the ring on the rod. Your expression must contain no symbols other than k, q1, q2, R and L.

Answer 1