Hertz high-energy, or, equivalently, massive particles, although these are not directly observable and must be inferred from their interactions with other phenomena. By convention, these are typically not expressed in hertz, but in terms of the equivalent quantum energy, which is proportional to the frequency by the factor of Planck's constant. Hertz The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed
Rayleigh (unit) Rayleigh (unit) The rayleigh is a unit of photon flux, used to measure airglow (auroras, for example). It was first proposed in 1956 by Donald M. Hunten, Franklin E. Roach, and Joseph W. Chamberlain. It is named for John William Strutt, 3rd Baron Rayleigh (1842–1919). Its symbol is R (also used for the röntgen, an unrelated unit). SI prefixes are used with the rayleigh. One rayleigh (1 R) is defined as a column emission rate of 10 photons per square metre per column per second. Note that rayleigh is an apparent emission rate, as no allowances have been made for