Frequency Units:

Audible acoustic waves repeat at intervals which are only a small portion of a second. The minimum sound frequency a human being can hear is around 20 cycles per second, or 20 hertz. The maximum frequency an acoustic wave can contain and still be heard by a person with keen ears is a thousand times higher i.e., 20,000 Hz.

The radio waves travel in a diverse medium than sound waves. Their minimum frequency is a few thousand hertz, and their maximum frequencies range into the trillions of hertz. Infrared (IR) and visible-light waves take place at frequencies much greater than radio waves. The ultraviolet (UV) waves, x-rays, and gamma (γ) rays range into quadrillions and quintillions of hertz, vibrating more than 1 trillion times more rapidly than middle C on the musical scale.

To represent high frequencies, engineers and scientists use frequency units of kilohertz (kHz), megahertz (MHz), gigahertz (GHz), and terahertz (THz). Each of the unit is a thousand times higher than the preceding one in this succession. That is, 1 kHz = 1,000 Hz, 1 MHz = 1,000 kHz, 1 GHz = 1,000 MHz, and 1 THz = 1,000 GHz.