?

Electricity and Magnetism

Free Version

Upgrade subject to access all content

Easy

Rotation Direction of a Dipole in an Electric Field

EANDM-9WQE8F

Figure 1 depicts an electric dipole aligned along the $x$ axis, in a constant electric field.

Figure 1. “Timothy Black. Created for Albert.io. Copyright 2016. All rights reserved.”

The field is given by:

$$\vec{E} = -E_0 \hat{z}$$

…where $E_0$ is a positive constant. The positive and negative charges are arranged symmetrically about the $y$ axis, each being a distance $r$ from the axis.

Figure 2 shows four possible scenarios, $A$ through $D$, describing four possible senses in which the dipole can rotate when first encountering this electric field.

Figure 2. “Timothy Black. Created for Albert.io. Copyright 2016. All rights reserved.”

Which of these four scenarios best describes the initial rotation of the dipole?

A

Scenario $A$.

B

Scenario $B$.

C

Scenario $C$.

D

Scenario $D$.