The magnetic field generated by the currents is usually termed as the magnetic field B.B is sometimes called the magnetic flux density or the magnetic induction. The magnetic field is measured in Tesla. But when these fields produced are passing through the magnetic material, which has a magnetic field of its own, uncertainty can arise about what part of the magnetic field comes from external current and what part comes from the magnetic material itself. Therefore, we define a term called magnetic field strength (H) to explain the concept.H has the unit amperes/meter.
The relationship between the magnetic field (B) and the magnetic field strength (H) is given by
H = B/μm = B/μ0 – M
M = magnetisation of the material
μ0 = magnetic permeability of space