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 Wave speed

The wave equation:

Wave speed (m/s) = Frequency (Hz) x Wavelength (m)

In your exams, you may be asked to find one of these, given 2 of them. The easiest way to manipulate the equation is to use the Wave triangle:


Frequency(Hz) = Speed/ Wavelength

Wavelength (m) = Speed/Frequency

*Just make sure you have changed the units correctly before you do the calculation.


In some calculations, it may seem that you have been given only one variable before the calculation, for example;

It takes a mobile phone signal 0.002 seconds to reach your friend's phone. How far away is your friend? Here you have been given only the time. This is because they assume that you know that all electromagnetic waves travel at the same speed i.e. 300 000 000 m/s.

And of course you know that Speed = Distance /Time

So Distance = Speed / time


All electromagnetic waves i.e. light, x rays, microwaves, radio waves, infra red waves travel at 300 000 000 m/s through the air.