Magnetic Dipole Moment does not include the permeability of free space?

1. Jun 7, 2005

H_man

Magnetic Dipole Moment does not include the permeability of free space???

Hi,

The formula for a magnetic field in a current loop involves the permeability of free space.

But the formula for the magnetic dipole moment which seems to represent the flux through a current loop does not incorporate the permeability of free space.

Whats happening here?

2. Jun 7, 2005

Meir Achuz

It's just a question of where you put the constant mu0.
It's not usually put in the mag mom. Then mu0/4pi is put into the Eq. for B, just as it is for B due to currents.
The mag mom is NOT the flux through a current loop.

3. Jun 7, 2005

Crosson

Anything that you measure involving the magnetic moment also involves a magnetics field, and the permeability is included in that magnetic fielc.

4. Jun 7, 2005

H_man

Thanks for that, though its still not entirely clear.

What exactly is the Magnetic Dipole Moment a measure of then?

I ask this as I know in the Stern Gerlach exp. the Ag atoms experience a torque due to the dipole moments of the electrons being acted upon by the magnetic field into which it enters. And I originally assumed that the dipole moment was a way of stating the magentic field strength of the current loop....

5. Jun 7, 2005

Crosson

It is a measure of how strong the interaction between that dipole and an external magnetic field would be.

6. Jun 7, 2005

Gokul43201

Staff Emeritus
Use the analogue of the electric dipole moment. This is simply the charge times a separation. You do not see $\epsilon_0$ anywhere, do you ?

Likewise, there is no reason for the magnetic dipole moment to have $\mu_0$ in it. This is by definition.

Last edited: Jun 7, 2005
7. Jun 8, 2005

H_man

Thanks guys, its all much clearer now.