Electromagnetism is a branch of physical science that involves all the phenomena in which electricity and magnetism interact. This field is especially important to electronics because a magnetic field is created by an electric current. The rules of electromagnetism are responsible for the way charged particles of atoms interact.

Some of the rules of electrostatics, the study of electric charges at rest, were first noted by the ancient Romans, who observed the way a brushed comb would attract particles. It is now known that electric charges occur in two different types, called positive and negative. Like types repel each other, and differing types attract.

The force that attract positive charges to negative charges weakens with distance, but is intrinsically very strong. The fact that unlike types attract means that most of this force is normally neutralized and not seen in full strength. The negative charge is generally carried...