Hertz radians per second. Thus a disc rotating at 60 revolutions per minute (rpm) is said to be rotating at either 2 rad/s "or" 1 Hz, where the former measures the angular velocity and the latter reflects the number of "complete" revolutions per second. The conversion between a frequency "f" measured in hertz and an angular velocity "ω" measured in radians per second is The hertz is named after the German physicist Heinrich Hertz (1857–1894), who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission (IEC) in 1930. It was adopted by
Hartley (unit) digit, a ban corresponds to a decimal digit. A deciban is one tenth of a ban; the name is formed from "ban" by the SI prefix "deci-". One hartley corresponds to log(10) bit = ln(10) nat, or approximately 3.322 Sh, or 2.303 nat. A deciban is about 0.332 Sh. Though not an SI unit, the hartley is part of the International System of Quantities, defined by International Standard IEC 80000-13 of the International Electrotechnical Commission. It is named after Ralph Hartley. The term "hartley" is named after Ralph Hartley, who suggested in 1928 to measure information using a logarithmic base