Voltage against the strength of an electromagnet. It seems the strength grows exponentially in an experiment I have done, but I don't know if this should be the case. If so, why does it happen? The graph is telling me that if I add a little bit more voltage when it is already quite high I get a lot more strength than if the same amount was added when it was low. I would have thought it might have gone the other way round, but I don't really know anything hence me asking. Thanks for any help. Also does anyone know any good websites I can learn about electromagnets, as in why/how they work.