Light

Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific setting, electromagnetic radiation of any wavelength. The three basic dimensions of light (i.e., all electromagnetic radiation) are:

Visible electromagnetic radiation

Visible light is the portion of the electromagnetic spectrum between the frequencies of 380 THz (3.8×1014 hertz) and 750 THz (7.5×1014 hertz). The speed (c), frequency (f or u), and wavelength (lambda) of a wave obey the relation:

Related Topics:
Electromagnetic spectrum - Frequencies - THz - Hertz

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: c = f~lambda ,!

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Because the speed of light in a vacuum is fixed, visible light can also be characterised by its wavelength of between 400 nanometres (abbreviated 'nm') and 800 nm (in a vacuum).

Related Topics:
Speed of light - Wavelength - Nanometre - Vacuum

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Light excites the rod cells and cone cells in the retina of the human eye, creating electrical nerve impulses that travel up the optic nerve to the brain, producing vision.

Related Topics:
Rod cell - Cone cell - Retina - Human eye - Electric - Optic nerve - Brain - Vision

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