Hertz facts for kids
The hertz (symbol: Hz, definition: 1/s) is a unit derived from time which measures frequency in the International System of Units (SI). Frequency is how often something happens. A frequency of 1 hertz means that something happens once a second. The note Middle C (the C in the middle of the piano) is 261.65 (262) Hz. This means there are 262 vibrations every second, which is heard as the note Middle C, when that piano key is played.
Humans are able to hear sounds between 20-20 000 Hz. Owls are able to hear sounds between 200–12000 Hz.
The basic unit is 1/second. The unit is named after a German physicist Heinrich Rudolf Hertz.
Contents
Multiple units
1000 hertz is 1 kilohertz. 1000 kilohertz is 1 megahertz, 1000 megahertz is 1 gigahertz: (see table)
| Unit | Equal to: |
|---|---|
| Kilohertz (KHz) | 1000 Hz |
| Megahertz (MHz) | 1000 kHz |
| Gigahertz (GHz) | 1000 MHz |
| Terahertz (THz) | 1000 GHz |
| Petahertz (PHz) | 1000 THz |
| Exahertz (EHz) | 1000 PHz |
| Zettahertz (ZHz) | 1000 EHz |
| Yottahertz (YHz) | 1000 ZHz |
Examples
- The frequency of the Earth's spinning (once per ~24 hours) is about 12 microhertz (much smaller than 1 Hz).
- The hertz is sometimes used to measure the power of a processor in computing and electronics.
- Amateur radio in the United States Of America is at different frequencies between 1.8 and 1300 MHz
- Air traffic control uses frequencies between 3 and 25 MHz as well as frequencies between 108 and 136 MHz
- Musical note middle G (G4) has a frequency of 392 Hz.
Images for kids
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Top to bottom: Lights flashing at frequencies f = 0.5 Hz, 1.0 Hz and 2.0 Hz; that is, at 0.5, 1.0 and 2.0 flashes per second, respectively. The time between each flash – the period T – is given by 1⁄f (the reciprocal of f ); that is, 2, 1 and 0.5 seconds, respectively.
See also
In Spanish: Hercio para niños
