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:

Light sources

There are many sources of light. A body at a given temperature will emit a characteristic spectrum of black body radiation. Examples include sunlight (the radiation emitted by the chromosphere of the Sun at around 6,000 K peaks in the visible region of the electromagnetic spectrum), incandescent light bulbs (which are generally very inefficient, emitting only around 10% of their energy as light and the remainder as "heat", i.e. infrared) and glowing solid particles in flames (see fire, red hot, white hot).

Related Topics:
Temperature - Black body - Sunlight - Chromosphere - Sun - K - Incandescent light bulb - Fire - Red hot - White hot

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Atoms emit and absorb light at characteristic energies. Emission lines can either be stimulated, such as visible lasers and microwave maser emission, light-emitting diodes, gas discharge lamps (such as neon lamps and neon signs, mercury-vapor lamps, etc), and flames (light from the hot gas itself - so, for example, sodium in a gas flame emits characteristic yellow light) or spontaneous.

Related Topics:
Emission line - Stimulated - Laser - Maser - Light-emitting diode - Gas discharge - Neon lamp - Neon sign - Mercury-vapor lamp - Sodium - Spontaneous

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Acceleration of a free charged particle, such as an electron, can produce visible radiation: Cyclotron radiation, Synchrotron radiation, and Bremsstrahlung radiation. Particles moving through a medium faster than the speed of light in that medium can produce visible Cherenkov radiation.

Related Topics:
Electron - Cyclotron radiation - Synchrotron radiation - Bremsstrahlung - Cherenkov radiation

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Certain chemicals produce visible radiation by chemoluminescence. In living things, this process is called bioluminescence: for example, fireflies produce light by this means, and boats moving through water can disturb glowing plankton.

Related Topics:
Chemoluminescence - Bioluminescence - Fireflies

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Certain substances produce light when they are illuminated by more energetic radiation, a process known as fluorescence. This is used in strip lights.

Related Topics:
Fluorescence - Strip light

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Particles striking certain chemicals can produce light by phosphorescence, for example, cathodoluminescence. This mechanism is used in oscilloscopes and televisions, and cathode ray tube.

Related Topics:
Phosphorescence - Cathodoluminescence - Oscilloscope - Televisions - Cathode ray tube

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Certain other mechanisms can produce light:

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• scintillation
• scintillator
• electroluminescence
• bioluminescence
• sonoluminescence
• triboluminescence
• radioactive decay
• particle-antiparticle annihilation