Dipole moment & Gauss Law

 

Magnetic Dipole moment

For z>>R:

BL = (u0/4π)(2AI/z3)

• Where A is the area of the loop and I is the current. Definition of magnetic dipole moment: 

u = (N)AI

• The quantity AI is what determines “how strong” the magnet is

• Do not get u and u0 confused in calculations.

Magnetic Dipole moment - Direction

The magnetic dipole moment is perpendicular to the loop in the direction of the right-hand rule

 

Gauss’ Law Review

Remember the idea of the surface integral?

It looked like vector calculus, but turned out to be mostly multiplication.

 

This led to Gauss’ Law,  which looked complicated, but mostly reduced to:

EA = Qin/ε0

Which could be used to find the value of E without integration in some cases.