Formula for force in magentic field

[anam]

Does anyone have formulas for working out the attracting force of a ferromagnetic object while in a magnetic field.

I am looking at in particular the force of an object if caught in the magnetic field of an MRI scanner, or the missile effect as it is called.

Anam

[pervect]

The energy in a magnetic field is \frac{B^2}{2\mu} where [tex]\mu[tex] is the permittivity.

To get the force, I think you'll have to integrate the total energy of the magnetic field as a function of position, and take the partial derivative with respect to position.