In Example $22\mathrm{.}9($Section $22\mathrm{.}4)$ we found that the electric field inside a uniformly charged sphere with positive charge

$$

and radius

$$

points radially outward from the center of the sphere and has magnitude

$$

$=$

$$

$$

$/$

$4$

$$

in

$0$

$$

$3$

at a distance

$$

from the center. $($a$)$ By integrating the electric field, find the potential difference between the center of the sphere and its surface. $($b$)$ Which is at higher potential: the center or the surface?