An electric dipole of moment $\vec{p}$ is lying along a uniform electric field $\vec{E}$. The work done in…
An electric dipole of moment $\vec{p}$ is lying along a uniform electric field $\vec{E}$. The work done in rotating the dipole by rotating the dipole by 90 degrees:
$p E$
$\sqrt{2} p E$
$p E / 2$
$2 P E$
Solution
Work done
$\begin{aligned}
W & =\int_0^\theta P E \sin \theta d \theta \\
& =P E(1-\cos \theta) \\
\therefore \quad \text { Since } \theta & =90^{\circ} \\
W & =P E(1-\cos 90) \\
Q & =P E
\end{aligned}$