a
(a) Electric potential at equatorial point of a small dipole moment $=P(\text { at } r)$
As we have learned,
if, $r>>1$
$E_{a x i}=\frac{1}{4 \pi \in_{0}} \frac{2 P}{r^{3}}$
$V_{a x i}=\frac{1}{4 \pi \in_{0}} \frac{P}{r^{2}}$
where,
angle between $E_{a x i}$ and $P$ will be $0$