Gauss’s law for magnetism states that the net magnetic flux through
any closed surface is zero
0
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S
B
iS
B
all area
elements
5 Consider a material placed in an external magnetic field B0 The
magnetic intensity is defined as,
0
= Bµ0
H
The magnetisation M of the material is its dipole moment per unit volume The magnetic field B in the material is,
      B = m0 (H + M)
6