A uniformly charged ring has a radius R and a total charge Q. Find the electric field vector E along

A uniformly charged ring has a radius R and a total charge
Q. Find the electric field vector E along the ring axis at a point on the
normal to the ring plane at a distance b from the ring center.

Consider a metal sphere with a radius R, charged with a
total charge Q. Determine the energy of the electric field inside and outside
the sphere and the capacitance of the sphere.