# Magnetic dipole derivations

this is not homework help.I want to know.

Hello,can any one suggest why for a dipole m placed in a magnetic field B
and N=mxB?

siddharth
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Gold Member
Hello,can any one suggest why for a dipole m placed in a magnetic field B
and N=mxB?

Take an infinitesimal current loop of arbitrary shape and use the Lorentz force law.

Meir Achuz
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Gold Member
Take an infinitesimal current loop of arbitrary shape and use the Lorentz force law.
That will work, but the derivation is a bit involved for an arbitrary shape.
If you are satisfied with doing it for a rectangular loop, that is easier for the torque. Once you know the torque, you can show U=-mu.B, and then