What is an electromanget?

How does electricity produce magnetism in an electromanget?

Any moving electrical charge - and therefore, also, any electrical current - is surrounded by a magnetic field.As to why this is so, you can either accept it as a fact, or read some advanced scientific papers; I believe the Theory of Relativity explains the relationship between electricity and magnetism, though I don't know the details myself. Einstein's paper, "On the Electrodynamics of Moving Bodies", might be a good place to start.