9)
Rationalised 2023-24
Physics
146
 EXAMPLE 5 5
where Bm is the field contributed by the material core It turns out that
this additional field Bm is proportional to the magnetisation M of the
material and is expressed as
Bm = m0M
(5 10)
where m0 is the same constant (permittivity of vacuum) that appears in
Biot-Savart’s law