Question

An electric dipole of length $4cm$,when placed with its axis making an angle of ${60}^o$ with a uniform electric field, experience a torque of $4\sqrt{3}$Nm. Calculate the potential energy of the dipole if it has charge $\pm 8nC$.

Answer 1

$U=-pe\cos \theta$
$=-p^{-1}.E^{-1}$
$-p\cos {60}^o$
$=-8\times 1$
$=-43$
$=PE\sin \theta$
$4\sqrt{3}=PE\sin {60}^o$
$4\sqrt{3}=PE\frac{\sqrt{3}}{2}$
$PE=8$