A nonconducting sphere has radius $R=2\mathrm{.}56cm$ and uniformly distributed charge $q=+6\mathrm{.}50fC.$ Take the electric potential at the sphere's center to be $V_0=0.$

$($a$)$ What is $V$ at radial distance $r=1\mathrm{.}45cm?$

V

$($b$)$ What is $V$ at radial distance $r=R?$

V