Finding Electric Potential of concentric shells

[ltkach]

A thin spherical shell with radius = 3.00 is concentric with a larger thin spherical shell with radius 7.00 . Both shells are made of insulating material. The smaller shell has charge distributed uniformly over its surface, and the larger shell has charge distributed uniformly over its surface. Take the electric potential to be zero at an infinite distance from both shells.

a)What is the electric potential due to the two shells at the following distance from their common center: r = 0?

b) r=0.04m

c) r = 0.08

d) What is the magnitude of the potential difference between the surfaces of the two shells?

e)which shell is at higher potential: the inner shell or the outer shell? why?

 

[kuruman]

This problem lacks the information to be solved with additional assumptions. For example, the lack of units next to numbers makes me guess that the radii of the shells are given in centimeters while distances from the common centers are given in meters. More importantly, the total charge on each shell is not given. Without that information questions (d) and (e) cannot be answered. Badly formulated problem.