The dipole moment $\vec p$ of a pair of charges $+q$ and $-q$ separated by $2\ell$ is directed:
AFrom $-q$ to $+q$
BAlong the equator of the dipole
CPerpendicular to the line joining them
DFrom $+q$ to $-q$
Answer & Solution
Correct answer: A. From $-q$ to $+q$
By convention $\vec p$ points from the negative charge to the positive charge and has magnitude $p = q \cdot 2\ell$. The equator is perpendicular to $\vec p$.