EM 3: Consider a solid insulating sphere with total charge Q and radius R. The volume
charge density for the sphere is given by,
$$
\rho(r) = \begin{cases}
A \left( 1 - \frac{r^2}{R^2} \right) & \text{for } r \le R \\
0 & \text{for } r > R
\end{cases}
$$
where A is a constant with the units of $$ \left[ \frac{C}{m^3} \right] $$.
a) Determine the constant A in terms of total charge Q and radius R.
b) Using Gauss's law, determine the electric field $ \vec{E}(r) $ for all points in the regions
0 < r < R and r > R
c) Determine the electric potential V(r) for all points in the regions 0 < r < R and
r > R.
d) Examine the continuity of the electric field and electric potential at the boundary
of r = R. Are they continuous? Why or why not?