Using Dirac delta functions in the appropriate coordinates, express the following charge distributions as three-dimensional charge densities ρ(x).
((a)) In spherical coordinates, a charge Q uniformly distributed over a spherical shell of radius R.
((b)) In cylindrical coordinates, a charge λ per unit length uniformly distributed over a cylindrical surface of radius b.
((c)) In cylindrical coordinates, a charge Q spread uniformly over a flat circular disc of negligible thickness and radius R.
((d)) The same as part (c), but using spherical coordinates.