Science 41

Two physicists are using glass prisms and investigating how a light beam’s trajectory is altered as it passes through.

Refraction is the bending of a wave when it enters a medium that changes the wave’s speed. When light passes from a fast medium to a slow medium the light ray bends toward the boundary between the two media. The amount of bending depends on the indices of refraction of the two media and is described quantitatively by Snell’s Law, which describes how the two angles mathematically relate.

Figure 1 shows the apparatus used to measure the refraction of light through a glass prism. Light from a source is forced through a narrow slit, to create a single beam of light. This beam is projected through the glass prism, and the light slows down and is “bent.” The trajectory (path) of the refracted light beam can be traced, as shown in the figure.

{Excerpt from “Refraction of Light” on}

White light is actually a combination of several different colors of light. When white light is directed through a prism, the refraction separates the colors into distinct beams, as seen in Figure 2.

The faster traveling colors have longer wavelengths, and are refracted the least. The less refraction that occurs, the smaller the dispersion angle, as indicated in Figure 2.

Table 1 below presents the various colors that comprise white light, along with their wavelengths.