4. A nonconducting sphere with uniform charge density has a radius a and a total charge +2q; a noncon- ducting spherical shell (with uniform charge density) has an Inner radius b, outer radius c, and total charge -q. +29 Find expressions for the electric field in the regions (a) r c. For parts (e) through (h), now assume the sphere and shell are conductors (but with their net charges unchanged); find expressions for the electric field in the regions (e) r c