Hey, I'm working on an electromagnetic propulsion system (the one that is used in maglev trains) and I need a set of alternating north and south poles . It is kind of tedious to make each pole individually...so I have the following solutions for my problems..some of them may be wrong/ may not work so please help. 1) Alternating north and south poles A) Can I make a horseshoe type electromagnet by any chance? I need the poles like this. [N] [N] ..... AND SO ON. Can each [n] pair be a single electromagnet like a horseshoe? 2) I have to use dc right? I think the poles of an ac electromagnet keep changing based on the frequency of the ac used? Am I right. 3) Can I use a battery eliminator to supply dc from the mains? 4) I need to change the polarity of the electromagnet from time to time. Will reversing the current work. ( I am not using a soft iron core - can't find 'em) [*] I've just finished school. I'm going to be a fresher in university in a month and electrical engineering is my subject. I am spending my holidays by doing simple projects, just in case you wanted to know. thanks.