$1$ A spherical charge distribution is given by

${}_v=\{\begin{array}{cc}{}_o\frac{r}{a},& ra\end{array}$

Find $V$ everywhere.

$2$ Determine the electric field due to the following potentials:

$($a$)V=x^2+2y^2+4z^2$

$($b$)V=sin(x^2+y^2+z^2{)}^{\frac{1}{2}}$

$($c$)V={}^2(z+1)sin$

$($d$)V=e^{-r}sincos2$