A related constant which is useful when calculating with angular frequency instead of constant frequency is called (*) Dirac's constant, and is simply this constant divided by 2 pi.
Classical physics can be defined as the limit of quantum mechanics as this quantity tends to zero. It was originally proposed in reference to black-body radiation, where E, the quantized energy of the photons of radiation, equals this quantity times nu, the frequency. A related constant which is useful when calculating with angular frequency instead of constant frequency is called (*) Dirac's constant, and is simply this constant divided by 2 pi. It is denoted by the letter h and has a value of approximately 6.626 times 10-34 Joule-seconds. FTP, name this physical constant named after a German physicist, which describes the sizes of quanta.
Classical physics can be defined as the limit of quantum mechanics as this quantity tends to zero.
{Planck} constant or {Planck's} constant (prompt on {h} early, do not accept {h}-{bar})