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Electromagnetic spectrum and visible light
Generally, electromagnetic radiation (EMR) is classified by wavelength into radio waves, microwaves,
The … See more
Wikipedia
https://en.wikipedia.org/wiki/Light
Light - Wikipedia
Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz. The visible band sits adjacent to the infrared (with longer wavelengths … See more
1801
Young demonstrates light interference and supports wave theory of light.
1864
Maxwell shows that light is an electromagnetic wave and predicts its speed.
1971
Gabor wins the Nobel Prize for inventing holography, a technique of recording and displaying three-dimensional images of light.
1997
Chu, Cohen-Tannoudji, and Phillips win the Nobel Prize for using laser cooling and trapping to slow down and manipulate atoms.
Speed of light
The speed of light in vacuum is defined to be exactly 299 792 458 m/s (approx. 186,282 miles per second). The fixed value of the speed of light in SI units results from the fact that the metre is now defined in terms of the spee… See more
Optics
The study of light and the interaction of light and matter is termed optics. The observation and study of optical phenomena such as rainbows and the aurora borealis offer many clues as to the nature of light.
A … See more
Light sources
There are many sources of light. A body at a given temperature emits a characteristic spectrum of black-body radiation. A simple thermal source is sunlight, the radiation emitted by the chromosphere of the Sun at around 6,000 … See more
Measurement
Light is measured with two main alternative sets of units: radiometry consists of measurements of light power at all wavelengths, while photometry measures light with wavelength weighted with respect to a standa… See more
Light pressure
Light exerts physical pressure on objects in its path, a phenomenon which can be deduced by Maxwell's equations, but can be more easily explained by the particle nature of light: photons strike and transfer their momentum… See more
Historical theories about light, in chronological order
In the fifth century BC, Empedocles postulated that everything was composed of four elements; fire, air, earth and water. He believed that goddess Aphrodite made the human eye out of the four elements and that she lit t… See more
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Table of Contents
Electromagnetic spectrum and visible light
Speed of light
Optics
Light sources
Measurement
Light pressure
Historical theories about light, in chronological order