What is Light waves? — Physics

Definition 22.1 High School Physics · Chapter 22 — Light as a Wave: Diffraction and Interference

Monochromatic light — one pure color, which no prism can split further (Chapter 2) — is a periodic light wave: it crosses vacuum at $c = 3.00 \times 10^{8}\,\mathrm{m}/\mathrm{s}$ and is characterized by its frequency $f$ or its wavelength in vacuum $\lambda = c/f$ , the crest-to-crest distance of Chapter 20. The eye responds from about $400\,\mathrm{nm}$ (violet) to $800\,\mathrm{nm}$ (red); white light mixes the whole range.

Examples

Example 22.2 (Orders of magnitude)

A helium–neon laser emits red light of $\lambda = 633\,\mathrm{nm} = 6.33 \times 10^{-7}\,\mathrm{m}$ , so $f = c/\lambda \approx 4.7 \times 10^{14}\,\mathrm{Hz}$ : no electronics counts that fast — every wavelength in this chapter will be measured by geometry. For scale, a hair (about $70\,\text{µ}\mathrm{m}$ ) is a hundred wavelengths across. What waves? Not the air: an electric and magnetic field, honestly described in the Year 2 volume; only the wavelength matters below.

Read in context →

Examples

Related terms