Magnetic materials

  Permeability.  The property  of a material by virtue  of   Relative hich it allows  itself  to be magnetized is called  permeability  the ratio  B/H is called  permeability  of a material  and is the measure  of relative  magnetic  conductivity of materials permeability  varies  on the type of magnetic  material  amount  of saturation  and  temperature  permeability  is denoted  by 

The   magnetic  materials  Must have  high  permeability  so that  large  fluxes may be produced

   

Relative  permeability. The conductivity  power  of a substance  for magnetic  lines  of force  as compared  with air is called  relative  permeability  . The value  of relative   permeability  varies  from material  to material  and  Also  depends  upon  the  degree  to which  the material  is magnetized it may have  a value  as high  as 2500 

          The  permeability        of a                      magnetic material  is given  by

 The  value  for the permeability  of free space  is 4pi×10^-10 H/m  . The permeability  of air is almost  the  same as that  for free  space