An electric dipole will have minimum potential energy when it subtends an angle $\left[\begin{array}{l} \cos…
An electric dipole will have minimum potential energy when it subtends an angle
$\left[\begin{array}{l}
\cos 0^{\circ}=1 \\
\sin 0^{\circ}=0
\end{array}\right]\left[\begin{array}{l}
\cos 90^{\circ}=0 \\
\cos \pi=-1
\end{array}\right]$
$\pi$ with direction of field.
$\frac{\pi}{2}$ with direction of field.
$\frac{3 \pi}{2}$ with direction of field.
zero with direction of field.
Solution
Potential energy of a dipole in an electric field is $-\vec{p} \cdot \vec{E}$
Potential energy is thus minimum when p and E in same direction.