Assume that we have some non-constant electric field $E(x,t)$ and a point-dipole at a position $q$ with a constant dipole moment $\vec{p}$. How would you describe the time evolution, i.e. the motion of such a dipole?
[Physics] Motion of a dipole in an electric field
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Best Answer
When an electric dipole is placed in a uniform electric field making an angle with the direction of the field as shown in the figure.
Force on charge $-q=-q\overrightarrow{E}$ (opposite to $\overrightarrow{E}$)
Force on charge $+q=q\overrightarrow{E}$ (along $\overrightarrow{E}$)
Thus, electric dipole is under the action of two equal and unlike parallel forces, which give rise to a torque on the dipole.
So, in a uniform electric field, an electric dipole experiences only a torque. But, when the electric field is non-uniform as you say, it experiences torque as well as net force.