**Derivation of Magnetic field Boundary Conditions**
One of Maxwell's equations state that for a magnetic field **B**

div**B**=0

Integrate over volume of interest and using

Gauss's law and the equation becomes

INTsc **B.ds**= 0

where INTsc refers to an area intergration over a closed

surface. If this imaginary area

incorporates two

materials equally, and noting that the

magnetic flux ψ is given by

ψ=INTs **B.ds**

then we can

conclude that

ψ_{1}=ψ_{2}

where ψ

_{1},ψ

_{2} are the magnetic fluxes in material 1 and material 2 respectively

..........................................

. ψ_{1} material 1

--------------------------------

ψ_{2}

material 2

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