Describe how an electromagnet is created? what makes it attract ferromagnetic materials?

A wire that has electrical current successively over it makes a magnetic field. Actually, the simplest electromagnet is a single wire that is twisted up and has an electric current consecutively through it. The magnetic field produced by the coil of wire is like a normal bar magnet. Only definite materials, for instance iron, nickel, cobalt, and gadolinium, display strong magnetic properties. These materials are called ferromagnetic. Ferromagnetic materials will react powerfully to magnets and can also be magnetized themselves. Often an electromagnet is enclosed around a core of ferromagnetic material, for example steel, which improves the magnetic field produced by the coil.

the part of the wave he is travelling on is the crest