![]() ![]() The characteristics of thermal radiation depend on various properties of the surface from which it is emanating, including its temperature, its spectral emissivity, as expressed by Kirchhoff's law. ![]() Electromagnetic radiation, including visible light, will propagate indefinitely in vacuum. This results in the electrodynamic generation of coupled electric and magnetic fields, resulting in the emission of photons, radiating energy away from the body. The kinetic interactions among matter particles result in charge acceleration and dipole oscillation. These atoms and molecules are composed of charged particles, i.e., protons and electrons. All matter with a nonzero temperature is composed of particles with kinetic energy. Thermal energy is the kinetic energy of random movements of atoms and molecules in matter. Thermal radiation reflects the conversion of thermal energy into electromagnetic energy. Thermal radiation is the emission of electromagnetic waves from all matter that has a temperature greater than absolute zero. Thermal radiation is also one of the fundamental mechanisms of heat transfer. Wien's displacement law determines the most likely frequency of the emitted radiation, and the Stefan–Boltzmann law gives the radiant intensity. Planck's law describes the spectrum of blackbody radiation, which depends solely on the object's temperature. If a radiation object meets the physical characteristics of a black body in thermodynamic equilibrium, the radiation is called blackbody radiation. Infrared radiation emitted by animals (detectable with an infrared camera) and cosmic microwave background radiation are examples of thermal radiation. : 73–86 Particle motion results in charge-acceleration or dipole oscillation which produces electromagnetic radiation. At room temperature, most of the emission is in the infrared (IR) spectrum. All matter with a temperature greater than absolute zero emits thermal radiation. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) is converted to electromagnetic radiation. Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Infrared cameras are capable of capturing this infrared emission (see Thermography). ![]() Its emission in the infrared is invisible to the human eye. Thermal radiation in visible light can be seen on this hot metalwork. Although this shows relatively high temperatures, the same relationships hold true for any temperature down to absolute zero. The peak wavelength and total-s radiated amount vary with temperature according to Wien's displacement law. Not to be confused with Heat-Ray (disambiguation). ![]()
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