The color ring inductor is a reactive device. Inductors are often used in electronic circuits. A wire is placed on an iron core or an air-core coil is an inductor. When the current passes through a section of wire, a certain electromagnetic field will be generated around the wire, and this electromagnetic field will have an effect on the wire in this electromagnetic field. We call this effect electromagnetic induction. In order to strengthen electromagnetic induction, people often wind an insulated wire into a coil with a certain number of turns, and we call this coil an inductance coil. For simple identification, the inductance coil is usually called an inductor or an inductor.