# How to find the strength of an electromagnet

by Pharrahnox
Tags: ampere's law, electromagnet, flux density, magnet, maxwell's equation, measure, strength
 P: 87 I have created a simple electromagnet that is just an iron railroad spike with some thick insulated wire wrapped around it. This is connected to a dodgy, old motorbike battery (I'm thinking of being a decent battery...). I have looked up how you measure the strength, but I'm not sure what is the one I'm looking for. Is it magnetic flux density? If so, I found the formula for teslas: T = N/Am. How can I apply this to my magnet? I can find the Amperes with a multimeter, but I don't know how to find the Newtons... Also, with the metres part, is that the length of iron wrapped in the coil, or just the length of iron all together?
 HW Helper P: 6,214 You can look up the magnetic permeability of the iron core. Get the current from the battery and use the formula for the magnetic field of a solenoid. http://hyperphysics.phy-astr.gsu.edu.../solenoid.html
 P: 87 Ok, thankyou, the link was very helpful. I'm not sure if I should start a new thread for this or not, but I'm hoping there is an easy answer. I also have a horse-shoe shaped permanent magnet, and I was wondering how I can figure out its strength, to compare with electromagnets that I will build.

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