Hen a wire carrying a current is wound into a series of loops called coils, each turn of the wire produces a magnetic field. The magnetic fields produced by these turns add together to produce a stronger magnetic field. A magnet formed in this way is called an electromagnet. If you insert certain kinds of metal, such as iron, into the coil, the strength of the magnetic field increases even more. Iron contains tiny regions called domains that act like tiny magnets. Normally the domains point in all different directions. As a result, the iron metal is not magnetic. When an electric current passes through the coils, however, the domains line up. This adds to the strength of the electromagnet. The diagram shows a simple electromagnet with a wire coiled around a nail.
Think about another factor that might affect the strength of the magnetic field around an electromagnet. Express this as a question that you could answer through an investigation
please help!