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.
The adductors are fan-like muscles in the upper thigh that pull the legs together when they contract. They also help stabilize the hip joint. The adductors attach from the pelvis to the femur (thigh bone). The most common cause of groin pain is a muscle strain that causes localized pain in the inner thigh or groin. A severe tear can cause a sudden, acute pain and may be accompanied by swelling and bruising.