lockedup
Sep21-09, 02:16 AM
1. The problem statement, all variables and given/known data
Determine a formula for the total resistance of a spherical shell made of material whose conductivity is \sigma and whose inner and outer radii are r1 and r2. Assume the current flows radially outward.
2. Relevant equations
\sigma = 1/\rho
R = (\rho*l)/A
3. The attempt at a solutionSince the current is moving outward, l (length) is going to be the difference of the radii. How do I account for the changing surface area?
The solution is (r1 - r2)/(4\pi*\sigma*r1*r2)
EDIT: *facepalm* I spelled hollow wrong...
Determine a formula for the total resistance of a spherical shell made of material whose conductivity is \sigma and whose inner and outer radii are r1 and r2. Assume the current flows radially outward.
2. Relevant equations
\sigma = 1/\rho
R = (\rho*l)/A
3. The attempt at a solutionSince the current is moving outward, l (length) is going to be the difference of the radii. How do I account for the changing surface area?
The solution is (r1 - r2)/(4\pi*\sigma*r1*r2)
EDIT: *facepalm* I spelled hollow wrong...