When you see the image of your face in a mirror, you are seeing the reflection of light from your face. Light reflects from a mirror at the same angle as it arrives. Below you can see waves of light reflecting off a mirror. You can think of light as being a kind of wave, similar to the waves in the ocean. The distance between the top of one wave and the top of the next wave is called a wavelength.
Different colors have different size wavelengths.
Violet has the shortest wavelength. Red has the longest wavelength. Wavelengths of colors are measured in nanometers, or billionths of a meter. Click on the slider on the right to change the angle of the incoming or incident light wave. Notice that the incident angle is always equal to the reflected angle.