Incandescence

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Incandescence

Incandescence is the emission of light

Light

Light, or visible light, is electromagnetic radiation of a wavelength that is Visible spectrum to the human eye , or up to 380?750 nm. In the broader field of physics, light is sometimes used to refer to electromagnetic radiation of all wavelengths, whether visible or not....
(visible electromagnetic radiation

Electromagnetic radiation

Electromagnetic radiation takes the form of wave propagation waves in a vacuum or in matter. EM radiation has an electric field and magnetic field component which oscillate in phase perpendicular to each other and to the direction of energy Wave propagation....
) from a hot body due to its temperature. The term derives from the verb incandesce, to grow white.

The incandescence of a theoretically perfectly black object is known as black body

Black body

In physics, a black body is an Physical body that absorbs all electromagnetic radiation that falls on it. No electromagnetic radiation passes through it and none is Reflection ....
radiation, which is described by relatively simple mathematical equations.

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Encyclopedia

Incandescence is the emission of light

Light

Electromagnetic radiation

Black body

Electromagnetic spectrum

The electromagnetic spectrum is the range of all possible electromagnetic radiation frequencies. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation from that particular object....
is described by Planck's law. The total power emitted by radiation from a black body is given by the Stefan–Boltzmann law. Wien's displacement law

Wien's displacement law

Wien's displacement law is a law of physics that states that there is an inverse relationship between the wavelength of the peak of the emission of a black body and its temperature....
predicts the wavelength of peak emission.

Incandescence occurs in incandescent light bulb

Incandescent light bulb

The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric light that works by incandescence, ....
s, because the filament resists

Electrical resistance

The electrical resistance of an object is a measure of its opposition to the passage of a steady electrical current. An object of uniform cross section will have a resistance proportional to its length and inversely proportional to its cross-sectional area, and proportional to the resistivity of the material....
the flow of electrons. This resistance heats the filament to a temperature where part of the radiation falls in the visible spectrum. The majority of radiation, however, is emitted in the invisible infrared part of the spectrum, which is why incandescent light bulbs are inefficient.

Fluorescent lamp

Fluorescent lamp

A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to Excited state mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluorescence, producing Light....
s do not function by means of incandescence, rather by a combination of thermionic emission

Thermionic emission

Thermionic emission is the heat-induced flow of charge carriers from a surface or over a potential-energy barrier. This occurs because the thermal energy given to the carrier overcomes the forces restraining it....
and atomic excitation

Excited state

Excitation is an elevation in energy level above an arbitrary baseline energy state. In physics there is a specific technical definition for energy level which is often associated with an atom being excited to an excited state....
due to collision with high energy electrons. In an incandescent lamp, only the electrons at the top of the band can participate. Higher temperature can increase efficiency but we do not have materials that can withstand much higher temperature.

Incandescence

See also