Help me clear up something. I know the magnetic field of an electromagnet's core is given by , where N is the number of turns of wire. Now, the resistance of the wire is given by R = ρ*λ/A, where ρ is the resistivity, and λ the length of the wire. Using Ohm's law to combine them, I get: But, disregarding the uncoiled ends, the length of the wire can be approximated as λ = n*N, where n is the length of one turn of wire. Replacing this in the last equation makes both Ns disappear, thus suggesting that, at least in steady state, the field strength is independant of the number of turns. Is this correct, or did I make a wrong step somewhere?