You are here:

# Physics/Electric dipole in an external field

Question
An electric dipole is placed in an external field which increases along Z direction, at the rate of 10^-7 N/m/C. The dipole movement is 10^-5 Cm and the dipole movement is oriented just opposite to the field. What is the torque and force experienced by the dipole?

Thanks.

It is not "dipole movement" it is "dipole moment". What this tells you is how much torque the dipole will feel when placed in a known electric field E. Since the dipole is oriented anti parallel to the electric field it will feel no torque at all. maximum torque on a dipole in an electric field occurs when the dipole moment is perpendicular to the field:
T = p x E = |p| * |E| * sin(Q) where p is the dipole moment and E is the electric field strength and Q is the angle between the dipole moment and the electric field vector.
As for th force the NET force on the dipole will be equal to the magnitude of the charge q at each end of the dipole and the electric field strength at that point in space:
Fnet = E1*q1 - E2*q2
You will Ned to know the length of the dipole to do this calculation in order to calculate the change in the electric field strength E at each end of the dipole.

Physics