Inductors and chokes prevent unwanted current fluctuations. The coil defines the general inductive element, while the choke is responsible for filtering the disturbances. In combination with capacitors, they make very good filters. Coils should be mounted in series. Coils and chokes are defined on the basis of their inductance expressed in henry [H]. The described components are most often used in devices that change direct current into alternating current and power-electric devices. They are the most universal electrical devices with many applications.