Q. The relation between the intensity of the electric field of an electric dipole at a distance r from its centre on its axis and the distance r is where ($r \gg 2l)$
A) $E \propto \frac{1}{r}$
B) $E \propto \frac{1}{r^{2}}$
C) $E \propto \frac{1}{r^{4}}$
D) $E \propto \frac{1}{r^{3}}$
Explanation
(d) Electric field due to an electric dipole at axial point
$E_{axial} = \frac{2kpr}{\left( r^{2} - l^{2} \right)^{2}}$
$If\ r \gg l,\ E_{a} = \frac{1}{4\pi\varepsilon_{0}}\frac{2p}{r^{3}}$
$\Longrightarrow E \propto \frac{1}{r^{3}}$
(directed from –q to +q)
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.