Question

What orientation of an electric dipole in a uniform electric field corresponds to its stable equilibrium?

Answer 1

Potential energy of dipole in uniform electric field is given by :
$$\begin{gathered} \mathrm{U}=-\overrightarrow{\mathrm{P}}.\overrightarrow{\mathrm{E}} \\ \mathrm{U}=-\mathrm{PE}\cos \mathrm{\theta } \end{gathered}$$
where θ is the angle between dipole moment and electric field.

when θ=0
​ U =− PE
hence, potential energy is minimum therefore it is the stable configuration.