Question

A dipole of dipole moment 0.5 Cm $\hat{i}$ is placed in an electric field $2\hat{i}+3\hat{j}\frac{N}{c}$. What is the net force and torque on the dipole?

• A.
• B.
• C.
• D. None of these

Answer 1

The correct option is C

The net force on a dipole in a uniform electric field is zero as both the charges experience force in equal and opposite directions. The torque however may or may not be zero depending on the orientation of the dipole.
$\overrightarrow{\tau }=\overrightarrow{p}\times \overrightarrow{E}$
Here, $\overrightarrow{p}=0.5\hat{i}$ $\overrightarrow{E}=2\hat{i}+3\hat{j}$
So $\overrightarrow{\tau }=0.5\hat{i}\times (2\hat{i}+3\hat{j})$
$=1.5\hat{k}\left(Nm\right)$