infrared

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Electromagnetic radiation of wavelengths longer than the red end of visible light and shorter than microwaves, roughly from 1 micron (10⁻⁶ m) to 350 microns. Infrared is divided into three spectral regions—near, mid and far infrared—but the boundaries between these are not agreed upon and can vary. The main factor that decides which wavelengths are included in each of the regions is the type of detector technology used. A typical breakdown is shown in the table “The Infrared Spectrum.” See infrared astronomy.

The Infrared Spectrum

Spectral Region	Wavelength Range (microns)	Temperature Range (K)	Objects Seen
Near infrared	1 to 5	740 to 3,000	Cooler red stars and red giants; dust is transparent
Mid infrared	5 to 40	140 to 740	Planets, comets, and asteroids; dust warmed by starlight, protoplanetary disks
Far infrared	40 to 350	11.6 to 140	Emission from cold dust; central regions of galaxies; very cold molecular clouds

The waves of the electromagnetic spectrum just outside the visible light spectrum, ≈ 30 to 430 THz frequency (just below red light).

An invisible band of radiation at the lower end of the visible light spectrum. With wavelengths from 750 nm to 1 mm, infrared starts at the end of the microwave spectrum and ends at the beginning of visible light. Infrared transmission typically requires an unobstructed line of sight between transmitter and receiver.

Widely used in most audio and video remote controls, infrared transmission is also used for wireless connections between computer devices (see IrDA) and a variety of detectors (see IR detector).

Infrared Can Be Anything Below Red

Infrared means "below red," and red frequencies are at the bottom of visible light. Therefore, infrared may refer to any type of invisible electromagnetic radiation below visible light, including AM, FM and TV. See infrared imaging, infrared wavelengths, IR remote control and IRED.

Infrared in the Spectrum

The infrared band comes after the microwave range and ends at visible light.

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adj. 1. (of electromagnetic radiation) having a wavelength just greater than that of the red end of the visible light spectrum but less than that of microwaves. Infrared radiation has a wavelength from about 800 nm to 1 mm, and is emitted particularly by heated objects.

2. (of equipment or techniques) using or concerned with this radiation: infrared cameras.

n.

the infrared region of the spectrum; infrared radiation.

See the Introduction, Abbreviations and Pronunciation for further details.

That region of the electromagnetic spectrum at wavelengths immediately above the visible spectrum; the heat in this region of the spectrum which is generated by a light source usually is undesirable (since it represents a loss in efficiency), but such heat is used in industrial applications for drying, baking a surface, etc.

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That portion of the electromagnetic spectrum with a wavelength longer than deep red light (wavelength between 7800 and 1,000,000 angstroms and just slightly longer than the longest wavelength of visible light), thus not visible but sensed as heat. See also near infrared and far infrared.

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of, pertaining to, or being infrared radiation.

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Denoting electromagnetic radiation of wavelength greater than that of the red end of the spectrum, having wavelengths of 0.75–1000 μm. Infrared rays are sometimes subdivided into long-wave or far infrared (about 3.0–1000 μm) and short-wave or near infrared (about 0.75–3.0 μm). They are capable of penetrating body tissues to a depth of 10 mm. Sources of infrared rays include heat lamps, hot water bottles, steam radiators and incandescent light bulbs.
Infrared rays are used therapeutically to promote muscle relaxation, to speed up the inflammatory process, and to increase circulation to a part of the body. See also heat.

See words rhyming with "infrared."

Dansk (Danish)
adj. - infrarød
n. - infrarødt område

Nederlands (Dutch)
infrarood

Français (French)
adj. - infrarouge
n. - infrarouge

Deutsch (German)
n. - Infrarot
adj. - infrarot

Ελληνική (Greek)
n. - υπέρυθρη ακτίνα
adj. - υπέρυθρος

Italiano (Italian)
infrarosso

Português (Portuguese)
n., -
adj. - infravermelho (m) (Fís.)

Русский (Russian)
инфракрасный

Español (Spanish)
adj. - infrarrojo
n. - luz infrarroja, rayos infrarrojos

Svenska (Swedish)
n. - infrarött
adj. - infraröd

中文（简体）(Chinese (Simplified))
红外线的, 红外线

中文（繁體）(Chinese (Traditional))
adj. - 紅外線的
n. - 紅外線

한국어 (Korean)
adj. - 적외선의, 적외선에 민감한
n. - 적외선

日本語 (Japanese)
adj. - 赤外線の
n. - 赤外線, 赤外部

العربيه (Arabic)
‏(الاسم) الأشعه تحت الحمراء (صفه) دون الأحمر, تحت الأحمر‏

עברית (Hebrew)
adj. - ‮תת-אדום, של קרניים תת-אדומות‬
n. - ‮קרניים באורך תדר גדול מזה של האור האדום (בלתי נראים)‬

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