For cyclical processes, such as rotation, oscillations, or waves, frequency is defined as a number of cycles per unit time. In physics and engineering disciplines, such as optics, acoustics, and radio, frequency is usually denoted by a Latin letter f or by the Greek letter or Î½ (nu) (see e.g. Planck's formula).
An inductor, also called a coil or reactor, is a passive two-terminal electrical component that stores electrical energy in a magnetic field when electric current is flowing through it. An inductor typically consists of an electric conductor, such as a wire, that is wound into a coil. When the current flowing through an inductor changes, the time-varying magnetic field induces a voltage in the conductor, described by Faraday's law of induction. According to Lenz's law, the direction of induced electromotive force (e.m.f.) opposes the change in current that created it.
Agitators and impellers are devices that top-loading washers use to move clothes during the wash cycles and, in the process, get rid of dirt and stains. An agitator is a spindle that sticks up in the center of an automatic washing machine's wash drum. The agitator is usually equipped with fins or vanes, and it twists and turns during the machine's wash cycle, moving clothes through the water and, ideally, removing dirt from them.