Visible light spans wavelengths from approximately 400 nm (violet) to 700 nm (red):
| Colour | Approximate wavelength (nm) |
|---|---|
| Violet | 400 |
| Blue | 470 |
| Green | 530 |
| Yellow | 580 |
| Orange | 600 |
| Red | 700 |
White light is a mixture of all visible wavelengths. A prism separates white light into a spectrum by refraction (different wavelengths refract by different amounts).
Colour of an object depends on which wavelengths it reflects or transmits.
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