Question

An electric dipole of moment → P is lying along uniform electric field. The work done in rotating the dipole by 90° is :

• A. $\sqrt 2pE$
• B. $\frac{pE}{2}$
• C. 2pE
• D. pE

Answer 1

Answer: (D)

pE

Answer 2

A torque = pE acts on an electric dipole when it is positioned in an electric field E.
The dipole is being rotated via an angle by this torque.
Work done by an external force is provided by if the dipole is rotated from angle 1 to 2.
W=pE (cos 1+cos 2)
(i) When we enter 1= 0° and 2 = 90° in Eq. (i), we obtain W=pE (cos0°cos90°)= pE(10) =pE.

Therefore, the correct option is (D): pE