There are several relationships between electricity and magnetism. We will explore them one by one. The first relationship we will discuss is how current flowing through a wire creates a magnetic field. A steady current creates a steady magnetic field like that created by a magnet.
We can create an electro-magnet by wrapping many turns of wire on a core, then causing an electrical current to flow through this coil of wire. With such a device we can create a magnetic field that can be controlled; we can turn it on and off by controlling the current. In fact, by controlling the current gradually, instead of just on and off as shown here, we could make the magnetic field gradually become stronger or weaker.
The strength of the field is proportional to the amount of current flowing and to the number of turns on the coil. Each turn of wire on the coil contributes to the strength of the magnetic field. If we double the number of turns, we can make an electro-magnet twice as strong. But, this exact ratio is only true if the current flow is the same for both coils.