Magnetic Flux
The number of magnetic lines of force passing through any surface is called magnetic flux linked with that surface.
Magnetic flux( phi;) = B. A = BA cos θ where B is magnetic field intensity or magnetic induction, A is area of the surface. Its unit is‘ weber’.
Magnetic Induction
The magnetic flux passing through per unit normal area, is called magnetic induction.
Magnetic induction( B) = φ / A Its unit is‘ waber / metre 2‘ or‘ tesla’. Magnetic of Material To describe the magnetic properties of materials, following terms are required
( i) Magnetic Permeability It is the ability of a material to permit the passage of magnetic lines of force through it.
Magnetic permeability( μ) = B / H where B is magnetic induction and H is magnetising force or magnetic intensity.
( ii) Magnetising Force or Magnetic Intensity The degree up to which a magnetic field can magnetise a material is defined in terms of magnetic intensity. Magnetic intensity( H) = B / μ
( iii) Intensity of Magnetisation The magnetic dipole moment developed per unit volume of the material is called intensity of magnetisation.
Intensity of magnetisation( I) = M / V = m / A where V = volume and A = area of cross-section of the specimen.
Magnetic induction B = μ o( H + I)
( iv) Magnetic Susceptibility( χm) The ratio of the intensity of magnetisation( 1) induced in the material to the magnetising force( H) applied, is called magnetic susceptibility.