A conducting spherical shell of radius Ri has a net charge Q on it. A larger, concentric spherical shell of radius Ro surrounds the inner shell. It has a charge -Q on it.

a) Using Gauss's law, find the electric field between the two shells.

b) By direct intergration, find the work required to move a test charge, qo, from the inner to the outer shell

c) Assuming both Q and qo are both negative charges, does moving the charge from the inner to the outer surface require the external agent to do positive work (i.e exert effort) or to do negative work?

d) What is the capacitance of this configuration of conductors?