I've been confused for awhile about this and I haven't found any decent explanatory answers. I read somewhere that the general formula for finding the force exerted by a solenoid electromagnet could be found by: Force = ((N x I)^2 x k x A) / (2 x s^2) where N is number of turns of a coil, I is the current passing through the coil, A is cross-sectional area of the solenoid, s is distance between solenoid and external object, k is permeability constant (4 x PI x 10^-7) Which part of this formula takes into account the inherent magnetic strength of the solenoid? I mean, wouldn't there be a difference in the force exerted if the solenoid was ferromagnetic instead of non-ferromagnetic? Because I also read that a ferromagnetic core like soft iron would amplify the magnetic strength of the electromagnet several hundreds even thousands of times. So how could I find the force that an iron core electromagnetic would exert using this formula? Thanks for any help..