Question

A small electric dipole is placed at origin with its dipole moment directed along positive x - axis. The direction of electric field at point $(2,2\sqrt{2},0)$ is

• A. along z - axis
• B. along y - axis
• C. along negative y - axis
• D. along negative z - axis

Answer 1

The correct option is B along y - axis


$tan\theta =\frac{y}{x}=\frac{2\sqrt{2}}{2}=\sqrt{2}$
or $cot\theta =\frac{1}{\sqrt{2}}$
$tan\varphi =\frac{tan\theta }{2}=\frac{\sqrt{2}}{2}$
$=\frac{1}{\sqrt{2}}=cot\theta$ $(tan\varphi =\frac{E_{\theta }}{E_r}=\frac{tan\theta }{2})$
$\therefore \varphi ={90}^{\circ }-\theta$
i.e, $\overrightarrow{E}$ is along positive y - axis.