Electricity and Magnetism

Free Version

Upgrade subject to access all content


Change in Speed of a Dipole in a Rotation


Figure 1A depicts the initial position of a dipole in a uniform electric field in the $xy$-plane, in which the dipole is perpendicular to the electric field direction. Figure 1B depicts the position of the dipole some time later, in which the dipole is aligned along the electric field direction.

Figure 1A and 1B

Timothy Black. Created for Albert.io. Copyright 2016. All rights reserved.

The magnitude of each of the two point charges is $q = 27.8 \rm{ mC}$, and the charges are separated by a distance $d = 62.3 \text{ mm}$ from one another. The mass of either charge is $m = 32.4 \text{ g}$. The electric field is:

$$\vec{E} = -2400 \hat{y} \ \rm{\text{N}/\text{C}}$$​

If the dipole is released from rest from the initial position, what will be the speed of either charge at the time depicted in Figure 1B?


$v = 16.0 \text{ m/s}$


$v = 8.00 \text{ m/s}$


$v = 12.6 \text{ m/s}$


$v = 11.33 \text{ m/s}$