2. Light, just like the sun's rays, travels through space in waves. Study figure 4 to recognize the basic parts of a wave. Wavelength 2 Crest Figure 4. Parts of a wave Photo credits: Julie C. Olermo Trough 3.) Light waves travel at a given velocity and wavelength. Wavelength is very important because it relates to the energy of light. Wavelength is designated by the Greek letter (.) lambda. The SI unit for wavelength (a) is meter, however you will commonly find wavelength written in nanometers (nm). Analyze figure 5, the Wavelength of Light. Longer wavelength has lower energy and shorter wavelength has higher energy. Figure 5. Wavelength of light wimmin low energy high energy Proto aedits:aute Colerano 4) The index of refraction is represented by the symbol (n) the ratio of the speed of light in vacuum and its speed in another medium. The index of refraction of a material is a quantity that compares the speed of light in that material to its speed in a vacuum. The refractive indices of the different colors of light indicate that light of different colors travels at different speeds in the prism which accounts for the different degrees of bending. The greater the index of refraction 6​