Light bends when it moves at an angle from one transparent substance, such as air, to another substance, such as water. This bending of light is called refraction. We call the substances that light can move through mediums. Water, glass, and air are mediums. Light refracts at different angles depending on the density of the medium. Light refracts more when moving through glass than when moving through water. This is true because glass is denser than water. Below you can explore how a light wave refracts as it moves from a vacuum to different mediums.

Use the medium menu to select a medium. Notice how the refraction angle changes as you change the mediums.

Click on the incident angle slider to change the angle of the light as it enters the medium.

You can change the wavelength of the light wave by clicking on the wavelength slider. 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.

You can learn more about the refraction of light and the color spectrum at our Light, Prisms and the Rainbow Connection activity site.

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