# Griffiths 4.12

1. Homework Statement
This question refers to Griffiths E and M book.

Of course I am stuck with the integral.

I chose z to be in the same direction as the polarization.

The integral is then
$$P \int d\Omega r'^2 dr'\frac{\left(\mathbf{r} -\mathbf{r'}\right)\cdot \hat{\mathbf{z}}}{\left(\mathbf{r} -\mathbf{r'}\right)^2}$$

BTW, how do you get the script r that Griffiths uses in latex?

2. Homework Equations

3. The Attempt at a Solution

Your denominator should be $$({\bf r-r')}^3$$.