What is a Wavelength?
The length of a repeating wave in which it passes through a complete cycle, returning to the starting point of the cycle. Wavelength is calculated by using the formula wavelength = velocity divided by frequency. This is an important parameter of waves and is the distance between two like points on the wave. The peak is the highest point of a wave and the valley is the lowest point of the wave.
When visible light travels through a prism, the wavelengths separate into the colours of the rainbow because each colour is a different wavelength. Violet has the shortest wavelength, at around 380 nanometers. Red has the longest wavelength at approximately 700 nanometers.