Question

A dipole of electric dipole moment p is placed in a uniform electric field of strength E. If $\theta$ is the angle between positive directions of p and E, then the potential energy of the electric dipole is largest when $\theta$ is

• A. $\frac{\pi}{4}$
• B. $\frac{\pi}{2}$
• C. $\pi$
• D. zero

Answer 1

Answer: (C)

$\pi$

Answer 2

The potential energy of an electric dipole in a uniform electric field is $u=-\vec{p}.\vec{E}$ $u=-p\, E cos\, \theta$ For u to be maximum $cos \theta=-1 \Rightarrow \theta=\pi$