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1. Homework Statement [/b]

A static charge distribution produces radial electric field as follows:

[itex]\stackrel{\rightarrow}{E}=A\frac{e^{-br}}{r}\stackrel{\rightarrow}{e_{r}}[/itex]

A,b are constants,please compute the charge density.

[itex]\nabla\cdot \stackrel{\rightarrow}{E}=\frac{\rho}{\epsilon}[/itex]

[itex]\nabla\cdot \stackrel{\rightarrow}{E}=\frac{1}{r^{2}}\frac{ \partial}{\partial r}(r^{2}A\frac{e^{-br}}{r})=\frac{1}{r^{2}}\frac{\partial}{\partial r}(Are^{-br})[/itex]

But the result is wrong.Can you tell me why?

A static charge distribution produces radial electric field as follows:

[itex]\stackrel{\rightarrow}{E}=A\frac{e^{-br}}{r}\stackrel{\rightarrow}{e_{r}}[/itex]

A,b are constants,please compute the charge density.

## Homework Equations

[itex]\nabla\cdot \stackrel{\rightarrow}{E}=\frac{\rho}{\epsilon}[/itex]

## The Attempt at a Solution

[itex]\nabla\cdot \stackrel{\rightarrow}{E}=\frac{1}{r^{2}}\frac{ \partial}{\partial r}(r^{2}A\frac{e^{-br}}{r})=\frac{1}{r^{2}}\frac{\partial}{\partial r}(Are^{-br})[/itex]

But the result is wrong.Can you tell me why?

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