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## Homework Statement

A coil with magnetic moment 1.40 Am^2 is oriented initially with its magnetic moment antiparallel to a uniform magnetic field of magnitude 0.830 T.

What is the change in potential energy of the coil when it is rotated 180 degrees, so that its magnetic moment is parallel to the field?

## Homework Equations

u = IA = magnetic moment

U = -uBcos(phi)

## The Attempt at a Solution

U1 = -uBcos(180) = -1.162J

U2 = -uBcos(360) = 1.162J

deltaU = U2-U1 = 1.162J - (-1.162J) = 2.324J

just wondering if I did the problem correctly, I'm not sure I have the correct angles; any help is greatly appreciated.