Consider a point charge $q=1.0 \mu \mathrm{C}$, point $A$ at distance $d_{1}=2.0 \mathrm{~m}$ from $q$, and point $B$ at distance $d_{2}=$ $1.0 \mathrm{~m} .$ (a) If these points are diametrically opposite each other, as in Fig. $25-28 a$, what is the electric potential difference $V_{A}-V_{B} ?$
(b) What is that electric potential difference if points $A$ and $B$ are located as in Fig. $25-28 b ?$