Solution
= Solution
On a simply connected region, $\nabla\times E=0$ gives $E=-\nabla\phi$. Then <Gauss's law> gives $\nabla^2\phi=-\rho/\varepsilon_0$.
= Solution
On a simply connected region, $\nabla\times E=0$ gives $E=-\nabla\phi$. Then <Gauss's law> gives $\nabla^2\phi=-\rho/\varepsilon_0$.