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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?

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Answer
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.

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James J. Kovalcin

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I am teaching or have taught AP physics B and C [calculus based mechanics & electricity and magnetism] as well as Lab Physics for college bound students. I have a BS in Physics from the University of Pittsburgh and a Master of Arts in Teaching from same. I have been teaching physics for 34 years. I am constantly updating my skills and have a particular interest in modern physics topics.

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