Explanation

(c) When a dipole AB of very small length is taken, then for a point p located at a distance r from the axis the electric field is given by
[image:1_image260.emf]
$E = \frac{1}{4\pi\varepsilon_{0}}.\frac{2p}{r^{3}}\ \ \ldots.(i)$
Where $p$ is dipole moment. When dipole is rotated by $90{^\circ},$ then electric field is given by
$E'''''''' = \frac{1}{4\pi\varepsilon_{0}}.\frac{p}{r^{3}}\ \ \ \ \ldots\ldots(ii)$
From Eqs. (i) and (ii), we get
[image:1_image261.emf]
$E^{''''''''} = \frac{E}{2}$