A hollow metal sphere has 6 cm and 10 cm inner and outer radii, respectively. The surface charge density on the inside surface is -100 nC/m^2. The surface charge density on the exterior surface is + 100 nC/m^2 .
What is the strength of the electric field at point 4 cm from the center?
What is the strength of the electric field at point 8 cm from the center?
Inner Surface Charge = n = Q/A
E = K*q/r^2
The Attempt at a Solution
Well I got the 1st one right:
Convert all the nC and cm to C and M.
E (at .04 m) =
= [K * q]/r^2
= [K * nA]/r^2
= [K * n(4(pi)R^2)]/r^2 (note R = inner sphere radius and r = 4 cm from center)
For the 2nd part I'm unsure. How do I found out the charge on the part of the sphere in between the hollow and exterior at 8 cm?
Is it q = nA - nA_2?
q = [1*10^-17 * 4pi(.1m)^2] - [-1*10^-17 * 4pi(.6m)^2]
Then repeat previous problem with E (at .08m)?