The relationship between wavelength, frequency, and the speed of light explains how electromagnetic waves behave as they move through space.
- Wavelength is the distance between two successive peaks (or troughs) of a wave. It tells you how long one complete cycle of the wave is.
- Frequency is the number of wave cycles that pass a fixed point in one second. It tells you how often the wave oscillates.
- Speed of light is the rate at which the wave travels through a medium—usually referring to its constant value in a vacuum.
These three are directly connected: when the frequency of a wave increases, the wavelength becomes shorter, and when the frequency decreases, the wavelength becomes longer. The product of frequency and wavelength always equals the speed at which the wave travels.
In a vacuum, this speed is always the same for all electromagnetic waves. So, if one of the two (frequency or wavelength) changes, the other must adjust to keep the speed constant.
This relationship helps explain why different colors of light (which have different frequencies and wavelengths) all move at the same speed in empty space.