As stated above, while infrared radiation is commonly referred to as heat radiation, only objects emitting with a certain range of temperatures and emissivities will produce most of their electromagnetic emission in the infrared part of the spectrum. However, this is the case for most objects and environments humans encounter in our daily lives. Humans, their surroundings, and the Earth itself emit most of their thermal radiation at wavelengths near 10 microns, the boundary between mid and far infrared according to the delineation above. The range of wavelengths most relevant to thermally emitting objects on earth is often called the thermal infrared. Many astronomical objects emit detectable amounts of IR radiation at non-thermal wavelengths. Radio spectrum. Provided by: Wikipedia. Located at: en.Wikipedia.org/wiki/Radio_spectrum. License: CC BY-SA: Attribution-ShareAlike Super high frequency. Provided by: Wikipedia. Located at: en.Wikipedia.org/wiki/Super_high_frequency. License: CC BY-SA: Attribution-ShareAlike X-ray spectroscopy. Provided by: Wiktionary. Located at: en.wiktionary.org/wiki/X-ray_spectroscopy. License: CC BY-SA: Attribution-ShareAlike

Natural sources of gamma rays include gamma decay from naturally occurring radioisotopes such as potassium-40, and also as a secondary radiation from atmospheric interactions with cosmic ray particles. Exotic astrophysical processes will also produce gamma rays.Atmospheric Transmittance: This is a plot of Earth’s atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation. Most UV wavelengths are absorbed by oxygen and ozone in Earth’s atmosphere. Observations of astronomical UV sources must be done from space.

Boundless. Provided by: Boundless Learning. Located at: www.boundless.com//physics/definition/thermal-agitation. License: CC BY-SA: Attribution-ShareAlike The optical window is also called the visible window because it overlaps the human visible response spectrum. This is not coincidental as humanity’s ancestors evolved vision that could make use of the most plentiful wavelengths of light.The near infrared (NIR) window lies just out of the human vision, as well as the Medium Wavelength IR (MWIR) window and the Long Wavelength or Far Infrared (LWIR or FIR) window though other animals may experience them. emissivity: The energy-emitting propensity of a surface, usually measured at a specific wavelength.

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Gamma rays are the highest energy EM radiation and typically have energies greater than 100 keV, frequencies greater than 10 19 Hz, and wavelengths less than 10 picometers. spectral color. Provided by: Wikipedia. Located at: en.Wikipedia.org/wiki/spectral%20color. License: CC BY-SA: Attribution-ShareAlike thermal agitation: The thermal motion of atoms and molecules in any object at a temperature above absolute zero, causing them to emit and absorb radiation. thermal radiation. Provided by: Wiktionary. Located at: en.wiktionary.org/wiki/thermal_radiation. License: CC BY-SA: Attribution-ShareAlike FM radio waves are also used for commercial radio transmission, but in the frequency range of 88 to 108 MHz. FM stands for frequency modulation, another method of carrying information. In this case, a carrier wave having the basic frequency of the radio station (perhaps 105.1 MHz) is modulated in frequency by the audio signal, producing a wave of constant amplitude but varying frequency.

Microwaves are used by microwave ovens to heat food. Microwaves at a frequency of 2.45 GHz are produced by accelerating electrons. The microwaves then induce an alternating electric field in the oven. Water and some other constituents of food have a slightly negative charge at one end and a slightly positive charge at one end (called polar molecules). The range of microwave frequencies is specially selected so that the polar molecules, in trying to maintain their orientation with the electric field, absorb these energies and increase their temperatures—a process called dielectric heating. The distinction between X-rays and gamma rays is somewhat arbitrary and there is substantial overlap at the high energy boundary. However, in general they are distinguished by their source, with gamma rays originating from the nucleus and X-rays from the electrons in the atom. radiograph. Provided by: Wiktionary. Located at: en.wiktionary.org/wiki/radiograph. License: CC BY-SA: Attribution-ShareAlike X-rays are broken up into broad two categories: hard X-rays with energies above 5-10 keV (below 0.2-0.1 nm wavelength) and soft X-rays with energies 100 eV – 5 keV (10 – 0.1 nm wavelength). Hard X-rays are more useful for radiography because they pass through tissue.

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emissivity. Provided by: Wiktionary. Located at: en.wiktionary.org/wiki/emissivity. License: CC BY-SA: Attribution-ShareAlike The distinction between X-rays and gamma rays has changed in recent decades. Originally, the electromagnetic radiation emitted by X-ray tubes almost invariably had a longer wavelength than the radiation (gamma rays) emitted by radioactive nuclei. Older literature distinguished between X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10 −11 m, defined as gamma rays. However, with artificial sources now able to duplicate any electromagnetic radiation that originates in the nucleus, as well as far higher energies, the wavelengths characteristic of radioactive gamma ray sources vs. other types, now completely overlap. Thus, gamma rays are now usually distinguished by their origin: X-rays are emitted by definition by electrons outside the nucleus, while gamma rays are emitted by the nucleus. The microwave region of the electromagnetic (EM) spectrum is generally considered to overlap with the highest frequency (shortest wavelength ) radio waves. Visible light, as called the visible spectrum, is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye. Electromagnetic radiation in this range of wavelengths is often simply referred to as “light”. A typical human eye will respond to wavelengths from about 390 to 750 nm (0.39 to 0.75 µm). In terms of frequency, this corresponds to a band in the vicinity of 400–790 THz. A light-adapted eye generally has its maximum sensitivity at around 555 nm (540 THz), in the green region of the optical spectrum. The spectrum does not, however, contain all the colors that the human eyes and brain can distinguish. Unsaturated colors such as pink, or purple variations such as magenta, are absent, for example, because they can be made only by a mix of multiple wavelengths. Microwaves can also be produced by atoms and molecules. They are, for example, a component of electromagnetic radiation generated by thermal agitation. The thermal motion of atoms and molecules in any object at a temperature above absolute zero causes them to emit and absorb radiation.