So, I'm playing around with electromagnets right now and I was wondering how to calculate (or determine experimentally) the approximate strength of the electromagnet. What I'm doing right now is using the formula for a solenoid, [tex]B=\mu_o N i[/tex] and adding the constant for whatever material is in the center (iron right now, so x200). The thing is, for the magnet I have sitting in my room right now I have i>.250mA (highest rating my multimeter goes to) which is giving me a magnetic field strength of 1.13T. So, this is kind of ridiculous and I don't think this is what I'm really getting so here lies the problem: Because I wrapped the wire around multiple times, does the distance from the iron core factor into the equation? It makes sense to me that each successive wrap will have less effect than the previous one. Also, I don't mind experimentally determining the value, but I'd like to have it in Tesla. Any idea how to convert data if I lift, say, a .5kg object into a tesla value at the surface of the magnet? Thanks for any help provided!