Cycles divided by time in seconds {cycles per second} (Hertz) (Hz) is frequency {frequency measurement}. Frequency is always a positive number. Alternating current is 50 Hz or 60 Hz.
Mechanical-object frequencies measure revolutions per minute (rpm). Car internal-combustion engines operate at 700 rpm to 6500 rpm.
Lowest frequency is one cycle during age of universe, 1/(10^21 s) = 10^-21 Hz. Lowest practical electromagnetic-wave frequency is 1 Hz (with wavelength 10^8 meters, one light-year).
By quantum mechanics, highest frequency {Planck frequency} is inverse Planck time 1/(10^-43 s) = 10^43 Hz. Highest practical electromagnetic-wave frequency is 10^23 Hz (with wavelength 10^-15 meters, electron diameter).
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Date Modified: 2022.0224