Thirteen wave cycles of a normal vibration
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Physics -- Units and Concepts: Speed |
Speed is distance per time. It is measured in metres per second or m/s. A more convenient unit is kilometres per hour, but that is not a metric unit, it's a "hybrid": part metric and part non-metric, a "bad unit".
Since there are 60x60=3'600 seconds in an hour, a speed of 1 m/s means we cover 3'600 m in an hour or go at 3.6 km/h, somewhat slower than walking speed.
At 10 m/s we do 36 km/h , like city traffic.
20 m/s is automobile speed: 72 km/h.
100 m/s is aircraft speed: 360 km/h.
1'000 m/s is about three times faster than the speed of sound (which is 343 m/s).
The speed of light is 300'000 km/s. This is also the speed with which electric signals travel in circuits.
Frequency gives the number of times a phenomenon repeats per second. The unit is 1/s (once per second), or Hertz, written Hz. Alternating current of electric sockets goes back and forth 50 times per second or at 50 Hz. The sound of the "la" of the middle octave of musical instruments makes the air vibrate at 440 times per second or at 440 Hz.
Thirteen wave cycles of a normal vibration
FM radio waves vibrate between 87 MHz and 108 MHz (megaHertz)
If a computer chip works at 1 GHz, its circuits will produce oscillations at 1 billion times per second. In that one second electricity can only go 300'000 km (in fact less inside cables) so each wave will be one billionth of that or 300'000'000'000 mm/1'000'000'000 = 300 mm or just 30 cm. It means that when one transistor lifts a signal up, 15 cm further down the wire the signal will actually be down... Therefore all electronics need to be close together. And it also means there is not much scope left for speed increases in computer chips.
