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 .