Hi. I have a solenoid, of length l, radius r, which has n turns of copper wire wound on it, carries a current of I amperes, and has a ferromagnetic core of relative permeability μr. How do I determine the magnetic field at a point in free space, x meters from the center of the solenoid? Also, how to calculate the force of attraction experienced by a ferromagnetic substance(whose magnetic properties are known) due to the same solenoid, placed at that point? Thanks for any reply.