Question

An electric dipole of dipole moment '$p$' is kept parallel to an electric field of intensity '$E$'. The work done in rotating the dipole through an angle of ${90}^o$ is :

• A. Zero
• B. $-pE$
• C. $pE$
• D. $2pE$

Answer 1

The correct option is C $pE$

Work done in rotating a electric dipole of dipole moment $p$ through angle $\theta$ from zero degree say is:
$W=-pE[\cos \theta -cos0]=pE-pE\cos \theta$
Here, $\theta$ is $90$ therefore work done, $W=pE$