Question

A dipole with the magnitude of dipole moment 0.5 C-m is placed in an external uniform electric field of magnitude $10\frac{N}{C}$. $\overrightarrow{p}$ makes an angle of ${60}^{\circ }$ with $\overrightarrow{E}$. What is the potential energy of the dipole in the current configuration provided that the potential energy is taken zero when dipole is perpendicular to the applied field?

• A. $-10J$
• B. $-5J$
• C. $zero$
• D. $-2.5J$

Answer 1

The correct option is D $-2.5J$

Potential energy is of a dipole in an external field is given by $\overrightarrow{-p}.\overrightarrow{E}$
$U\left({60}^{\circ }\right)=-0.5\times 10\times \cos \left({60}^{\circ }\right)=-2.5J$