Magnetic Field Sources - Magnetocaloric Energy Conversion: From Theory to Applications - page 41

B ¼ l 0 H ð 3 : 13 Þ

where

10 6 V

s
Am ¼

10 7 V

s
Am ¼

H
m

l 0 ¼ 1 : 256 4 p ð 3 : 14 Þ

is the empirically obtained permeability of free space (vacuum).
Here, there may be some confusion, since sometimes in publications we can see
B as the magnetic

eld. Note that in this particular case the authors tend to refer to
the applied magnetic eld in air (similar to vacuum).

ux must be preserved through any closed volume (if not, this
would require magnetic monopoles, which were hypothesized by Paul Dirac, and
have been recently been receiving attention again [ 8 , 9 ]). Therefore, the integral of
the magnetic

The magnetic fl

ux density through a certain volume, which is performed over the
surface (envelope) of that volume, is:
I

fl

dA

B

¼ 0 ð 3 : 15 Þ

This equation is equivalent to one of Maxwell ' s equations:

r B ¼ 0 ð 3 : 16 Þ

3.1.2 Magnetic Moment

The force acting on the conducting wire carries the current I and is placed in a
uniform magnetic eld H (Fig. 3.3 ) that is equal to:

Fig. 3.3 Force acting on a
conductor in a uniform
magnetic eld