The waves of the electromagnetic spectrum of about 430 to 750 THz frequency are visible to the human eye (other species vary in their sensitivities to such waves). The prism has long demonstrated that such light is a mixture of colours, a continuously changing range; Table 58 gives the nominal range of frequencies and wavelengths for the major colours, plus the nominal wavelength used for each (but see distinct values for cardinal illuminants in the CIE system).
| Frequency | Wavelength | Nomenclature |
|---|---|---|
| THz | nm | |
| (ultraviolet) | ||
| 749.5~ | 400.0 | |
| 731.2~ | 410.0 | violet |
| 707.1~ | 424.0 | |
| 637.9~ | 470.0 | blue |
| 610.3~ | 491.2 | |
| 576.5~ | 520.0 | green |
| 521.4~ | 575.0 | |
| 516.9~ | 580.0 | yellow |
| 512.5~ | 585.0 | |
| 499.7~ | 600.0 | orange |
| 463.4~ | 647.0 | |
| 461.2~ | 650.0 | red |
| 428.3~ | 700.0 | |
| (infrared) |
