creating a simple circuit requires a wire / battery & the wire's ends were connected to a battery ->  the wire's ends were connected to a simple circuit  the wire's ends were connected to a simple circuit & wire was looped several times around an iron nail ->  the wire is looped several times around an iron nail and is connected to a circuit  the wire is looped several times around an iron nail and is connected to a circuit & a electromagnet is formed by attaching an iron nail wrapped in a copper wire to a circuit ->  an electromaget is formed when a wire is looped around an iron nail and is connceted to a circuit  an electromaget is formed when a wire is looped around an iron nail and is connceted to a circuit & electromagnets generate magnetic fields -> a magnetic field will be generated when a wire is looped around an iron nail and is connected to a circuit