I am trying to create an electromagnet that will repel another magnet when activated. Currently, I am using a 12v battery with 7400 mAh. For the coil I am using copper wire of AWG 9 and 12 (I am experimenting with both sizes). I have also tried air and iron cores. However, I have run into a snag. The permanent magnet I am using is a disc NdFeB magnet. With the air core, the magnet has an effect on the coil but it is not strong enough. When I add the iron core, the NdFeB magnet is strongly attracted to the core regardless of whether or not the current is flowing and in what direction it is flowing. Is this because the current is too low (or the NdFeB magnet is too strong) that the effects of the electromagnet are null?? Also, The iron core is a solid piece of iron and i have the coil wrapped tightly around it. Will the electromagnet become stronger if I loosen the coil and leave an air gap between the coil and core?? Will an iron ring work better as a core compared to a solid piece? Any information is helpful. Thanks.