Science, Tech, Math › Science Wavelength Definition in Science Share Flipboard Email Print John Rensten/Getty Images Science Chemistry Chemical Laws Basics Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Todd Helmenstine Todd Helmenstine is a science writer and illustrator who has taught physics and math at the college level. He holds bachelor's degrees in both physics and mathematics. our editorial process Todd Helmenstine Updated January 11, 2020 The wavelength is a property of a wave that is the distance between identical points between two successive waves. The distance between one crest (or trough) of one wave and the next is the wavelength of the wave. In equations, wavelength is indicated using the Greek letter lambda (λ). Wavelength Examples The wavelength of light determines its color, and the wavelength of sound determines the pitch. The wavelengths of visible light extend from about 700 nm (red) to 400 nm (violet). The wavelength of audible sound range from about 17 mm to 17 m. Wavelengths of audible sound are much longer than those of visible light. Wavelength Equation The wavelength λ is related to the phase velocity v and the wave's frequency f by the following equation: λ = v/f For example, the phase speed of light in free space is approximately: 3×108 m/s so the wavelength of light is the speed of light divided by its frequency.