Frequency

How many complete oscillation cycles a wave or oscillator performs per second. Denoted f and measured in hertz (Hz), where 1 Hz = 1 cycle/second.

For a sinusoidal signal, frequency is the reciprocal of the period, f = 1/T. Angular frequency ω = 2πf is often more convenient in equations because it replaces factors of 2π with clean derivatives of sin(ωt) and cos(ωt). Energy in a wave scales as f², which is why high-frequency radiation (UV, X-rays, gamma rays) is far more energetic per photon than radio or microwaves.