# Magnetic flux density and susceptibility

#### Veerendra

What is the relation between magnetic suscptibility and magnetic flux density.

How can I know how much gauss I will need to attarct a mineral/oxide of given magnetic suscptibilty ?

#### Pmb

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Magnetic flux density == Magnetic Field

I thought that I should point out that the terms Magnetic flux density and Magnetic Field a synonymous. The later is more widely used.

What is the relation between magnetic suscptibility and magnetic flux density.
There is no such relationship. Magnetic susceptibility (which I'll label X) is the quantity which is defined through what's called a constitutive relation which relates the magnetic field in a material to the magnetization vector at the same point in material. For simple magnetic materials the relation is

M = XH

where

M = Magnetization

H = Magnetic field

How can I know how much gauss I will need to attarct a mineral/oxide of given magnetic suscptibilty ?
It will always be attracted regardless of the field strength. What the force is will be a different story

To know the force you need to state the nature of the material, i.e. volume, shape etc.

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#### Woody

I think what you are after (which is not exactly what you asked) is:

How can you work out the strength of Magnet required to move some objects,
given that you know the Magnetic susceptibility of the material the objects are made from.

As Pmb points out any resultant motion will depend on the objects size (etc.)
at least as much as it will on the Magnetic susceptibility of the material it is made from.