colour filter

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References

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Amendments 1-10 to the Constitution of the United States constitute what is known as the Bill of Rights on an American flag.

What Is the Emoluments Clause?

King Cobra snake in Malaysia. (reptile)

9 of the World’s Deadliest Snakes

Happy, smiling, flying pig

7 Everyday English Idioms and Where They Come From

Figure 13: A Maxim machine gun, belt-fed and water-cooled, operated by German infantrymen, World War I.

7 Deadliest Weapons in History

Periodical Cicada, Adult, Magicicada spp. Requires 17 years to complete development. Nymph splits its skin, and transforms into an adult. Feeds on sap of tree roots. Northern Illinois Brood. This brood is the largest emergence of cicadas anywhere

Why Do Some Cicadas Appear Only Every 17 Years?

Portrait of a mountain gorilla at a short distance. gorilla close up portrait.The mountain gorilla (Gorilla beringei beringei)

Falling Stars: 10 of the Most Famous Endangered Species

Cathedrale St.Jean in Lyon, France has a 14th-century astronomical clock that shows religious feast days till the year 2019; Perpetual Calendar

Ten Days That Vanished: The Switch to the Gregorian Calendar

colour filter

optics

Learn about this topic in these articles:

optical engineering

In optics: Filters and thin films
A colour filter is a sheet of transparent material that modifies a light beam by selective absorption of some colours in relation to others. A neutral filter absorbs all wavelengths equally and merely serves to reduce the intensity of a beam of light without changing its…
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