일반물리학 2 — Electric Potential: Problem 55

55 A nonconducting sphere has radius $R = 2.31\text{ cm}$ and uniformly distributed charge $q = +3.50\text{ fC}$. Take the electric potential at the sphere’s center to be $V_0 = 0$. What is $V$ at radial distance (a) $r = 1.45\text{ cm}$ and (b) $r = R$? (Hint: See Module 23-6.) (c) If, instead, $V_0 = 0$ at infinity, what is $V$ at $r = R$?