Torque on an electric dipole

Electricity and Magnetism Level 1

What is the torque on an ideal electric dipole with moment $\vec{p} = -A \hat{z}$ placed in an external electric field $\vec{E} = B \hat{z}?$

-AB None of these choices AB 0

1 solution

July Thomas
Jun 9, 2016

For an electric dipole,

$\tau = \vec{p} \times \vec{E}.$

But since $\hat{z} \times \hat{z} = 0,$ $\tau = 0$ for this problem.