Question

Consider a small electric dipole with magnitude of dipole moment p which is placed far away from point A as shown. The electric potential at the point A is

• A. exactly zero
• B. $\frac{k p }{r^2}$
• C. $\frac{- k p }{r^2}$
• D. $\frac{k p }{r}$

Answer 1

Answer: (C)

The magnitude of electric dipole moment is $p$. At a point distance $r$ from point $A$. In this situation the dipole moment tries to rotate the dipole as given in the above figure.
So, considering the position of $P$, the resultant potential at $A$ is
$ V_{A} =\frac{kp \,\cos\, \pi}{r^{2}} $
$=-\frac{k p}{I^{2}}$
$[\because\, \cos \pi=-1] $