Omega, in physics, is the last letter of the Greek alphabet and is used to represent the angular frequency of a wave. It is also used to represent the angular velocity of a rotating object. In electrical engineering, it is used to represent the unit of electrical resistance, the ohm. The ohm is a unit of measurement for electrical resistance, defined as the amount of resistance that will allow one ampere of current to flow through it when one volt of potential difference is applied across it.