Consider a solid conducting sphere with a radius a and charge Q1 on it. There is
ID: 1955334 • Letter: C
Question
Consider a solid conducting sphere with a radius a and charge Q1 on it. There is a conducting spherical shell concentric to the sphere. The shell has an inner radius b (with b > a) and outer radius c and a net charge Q2 on the shell. Denote the charge on the inner surface of the shell by Q'2 and that on the outer surface of the shell by Q''2 .
Point P lies between raidus a and radius b. Find the magnitude of the electric field at point P, where the distance P to the center of the solid conducting sphere is r = (a+b) / 2.
An example of the format of one of the answers is: EP = 4ke(Q1+Q2) / (a+b)2
There are 9 other answer choices though! Any help would be appreciated.
Explanation / Answer
You can ignore the shell because you are inside it. The only charge that matters is that on the solid conducting sphere.
Using Coulomb's Law, the field is:
kq/r2
= k(Q1)/((a+b)/2)2
= 4k(Q1)/(a+b)2