How to find the strength of an electromagnet

[Pharrahnox]

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?

 

[rock.freak667]

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/hbase/magnetic/solenoid.html

 

[Pharrahnox]

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.