Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light.
- InfraredVisible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).
- LightIt is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy mainly as light, ultraviolet, and infrared radiation.
- SunSlightly more than half of the energy from the Sun was eventually found, through Herschel's studies, to arrive on Earth in the form of infrared.
- InfraredThe main source of natural light on Earth is the Sun.
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Ultraviolet
2 linksUltraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays.
He called them "(de-)oxidizing rays" (de-oxidierende Strahlen) to emphasize chemical reactivity and to distinguish them from "heat rays", discovered the previous year at the other end of the visible spectrum.
The Sun emits ultraviolet radiation at all wavelengths, including the extreme ultraviolet where it crosses into X-rays at 10 nm.
Electromagnetic spectrum
2 linksRange of frequencies of electromagnetic radiation and their respective wavelengths and photon energies.
Range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies.
This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high-frequency (short wavelength) end.
The Sun emits its peak power in the visible region, although integrating the entire emission power spectrum through all wavelengths shows that the Sun emits slightly more infrared than visible light.
Sunlight
2 linksSunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light.
When direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat.
Visible spectrum
2 linksPortion of the electromagnetic spectrum that is visible to the human eye.
Portion of the electromagnetic spectrum that is visible to the human eye.
Electromagnetic radiation in this range of wavelengths is called visible light or simply light.
Under optimal conditions these limits of human perception can extend to 310 nm (ultraviolet) and 1100 nm (near infrared).
For example, Helium was first detected by analysis of the spectrum of the sun.