2.1.5 Characteristics of Waves: Speed

Now if you are watching a wave go by you will notice that they move at a constant velocity. The speed is the distance you travel divided by the time you take to travel that distance. This is excellent because we know that the waves travel a distance in a time T. This means that we can determine the speed.

There are a number of relationships involving the various characteristic quantities of waves. A simple example of how this would be useful is how to determine the velocity when you have the frequency and the wavelength. We can take the above equation and substitute the relationship between frequency and period to produce an equation for speed of the form.

Is this correct? Remember, a simple first check is to check the units! On the right-hand side we have velocity which has units m s^{- 1}. On the left-hand side we have frequency which is measured in s ^{- 1} multiplied by wavelength which is measured in m. On the left-hand side we have m s ^{- 1} which is exactly what we want.