- #1

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- Homework Statement
- Determine the electrostatic energy U stored in the sphere

- Relevant Equations
- ##W = ε_0/2 \int E^2d\tau## for all space

I tried to use ##W = ε_0/2 \int E^2d\tau## for all space. So I find that ##E = \frac{(R^3 - b^3)\rho}{3ε_0r^2}## where ##\rho## is the charge denisty. So from here when I plug the equation I get something like

$$W = \frac{(R^3 - b^3)^2\rho^2 4 \ pi}{18ε_0} \int_{?}^{\inf}1/r^2dr$$

Is this approach correct ?

At this point I get stuck for the boundry conditions. If I put R I get something meaningless