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This is a list of sources of light, the visible part of the electromagnetic spectrum.Light sources produce photons from another energy source, such as heat, chemical reactions, or conversion of mass or a different frequency of electromagnetic energy, and include light bulbs and stars like the Sun. Reflectors (such as the moon, cat's eyes, and mirrors) do not actually produce the light that ...
Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. [1] 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 .
Less than 5% of the energy they consume is converted into visible light; the rest is lost as heat. [1] [2] The luminous efficacy of a typical incandescent bulb for 120 V operation is 16 lumens per watt (lm/W), compared with 60 lm/W for a compact fluorescent bulb or 100 lm/W for typical white LED lamps. [3]
For example, for visible light, the refractive index of glass is typically around 1.5, meaning that light in glass travels at c / 1.5 ≈ 200 000 km/s (124 000 mi/s); the refractive index of air for visible light is about 1.0003, so the speed of light in air is about 90 km/s (56 mi/s) slower than c.
Richard Milhous Nixon was born on January 9, 1913, in what was then the township precinct of Yorba Linda, California, [1] in a house built by his father, on his family's lemon ranch. [2] [3] [4] His parents were Francis A. Nixon and Hannah (Milhous) Nixon. His mother was a Quaker, and his father converted from Methodism to the Quaker faith.
This is the list of episodes for the animated television series Martha Speaks.The series aired on PBS Kids from September 1, 2008 to November 18, 2014. Each episode focuses on mainly synonyms and vocabulary, featuring an underlying theme illustrated with a wide range of keywords, but can occasionally focus on introducing children to different science and other learning concepts, such as the ...
Stefani Joanne Angelina Germanotta [a] (born March 28, 1986), known professionally as Lady Gaga, is an American singer, songwriter and actress.Known for her image reinventions and versatility across the entertainment industry, she is an influential figure in popular music.
A light metal is any metal of relatively low density. [1] ... Their densities of 1.7, 2.7 and 4.5 g/cm 3 range from 19 to 56% of the densities of other structural ...