Question

A solid conducting sphere of radius 2.00 cm has a charge of 8x10^-6 C. A conducting spherical shell of inner radius 4.00 cm and outer radius 5.00 cm is concentric with the solid sphere and has a total charge of -4x10^-6 C. Find the electric field at (a) r=1.00 cm, (b) r=3.00 cm, (c) r=4.50 cm, and (d) r=7.00cm from the center of this charge configuration.