Question

An electric dipole of dipole moment $\overrightarrow{P}$ is placed parallel to the uniform electric field of intensity $\overrightarrow{E}$. On rotating it through ${180}^o$, the amount of work done is ________ .

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

Answer 1

The correct option is A $2PE$

Work done by external agent in rotating the dipole
$W=PE[\cos {\theta }_1-\cos {\theta }_2]$

Consider the initial angle to be

${\theta }_1=0$

and the final angle will be

${\theta }_2={180}^o$

So,$\Rightarrow$ $W=PE[cos{0}^o-cos{180}^o]=2PE$