The hertz (symbol: Hz) is a unit to measure frequency. It tells how often something happens. A frequency of 1 hertz means that something happens once a second. The pitch of the note Middle C (the C in the middle of the piano) is 262 Hz. This means there are 262 vibrations every second when a Middle C is played.
The unit is named after Heinrich Rudolf Hertz.
1000 hertz equals 1 kilohertz. 1000 kilohertz equals 1 megahertz, 1000 megahertz equals 1 gigahertz and so on.
- The frequency of the Earth's spinning (once per ~24 hours) is about 12 microhertz.
- The hertz is sometimes used to measure the power of a processor in computing and electronics.