- #1

Kashmir

- 437

- 72

##V (\mathbf r,t)= \frac{1}{4\pi\epsilon_0}\int \frac{\rho (\mathbf r',t_r) }{|\mathbf{ (r-r')}|}d\tau'##

Griffiths says:

" It is true that for a point source the denominator ## |\mathbf{(r-r')}|## comes outside the integral..."

Why does it come outside the integral?