How can i calculate pull force of a linear actuator(solenoid) with a NdFeB core?

I came across a formula F=[[sq(n*i)]*4*pi*10^(-7)*A]/2*sq(g). But the terms A and g aren't properly explained and also, the magnetic field of NdFeB core is completely neglected here.

16 March 2016 4,560 4 View