In a cylindrical core electromagnet,
Magneto-motive force (MMF) = 613 At
Magnetic strength (H) = 15345 At/m
I am using an iron core with 10% silicon in it, so the saturation magnetic flux density of that core is 1.95 T and absolute permeability (μ) = 1.2708·10-4 H/m. Area of cross-section (A) of the core = 1962.6 mm2.
I am having trouble calculating the force exerted by this electromagnet on a ferrous material at a distance (d) of 3 mm.
Substituting the above values in the formula, we get:
\$F_1 = 0.5\cdot\mu\cdot A\cdot \left({MMF \over d}\right)^2 = 5222~\text N\$
This force seems like too much.
Permeability of free space (μ0) = 1.2566·10-6 H/m.
If we use μ0 instead of μ, we get:
\$F_2 = 0.5\cdot\mu_0\cdot A\cdot \left({MMF \over d}\right)^2 = 51~\text N\$
Which one is correct and why?