Wavelength is the between one point on a wave and the nearest point just like it.

The wavelength is the distance between one point on a wave and the nearest point just like it. This could be, for example, the distance from one peak of a wave to the next peak, or from any point on a wave to the corresponding point on the next cycle of the wave.

Here are the steps to measure it:

1. Identify a point on a wave. This could be the crest (the highest point of the wave), the trough (the lowest point), or any point in between.

2. Find the next point on the wave that is in the same position. This means if you started at a crest, you would look for the next crest. If you started at a trough, you would look for the next trough.

3. Measure the distance between these two points. This distance is one wavelength.

4. It's often easier to measure this distance over several wavelengths and then divide by the number of wavelengths to get the average, as this can help reduce measurement errors.