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Prior to Kirchhoff's studies, it was known that for total heat radiation, the ratio of emissive power to absorptive ratio was the same for all bodies emitting and absorbing thermal radiation in thermodynamic equilibrium. This means that a good absorber is a good emitter. Naturally, a good reflector is a poor absorber.
In solar thermal collectors, a selective surface or selective absorber is a means of increasing its operation temperature and/or efficiency. The selectivity is defined as the ratio of solar radiation absorption (α sol ) to thermal infrared radiation emission (ε therm ).
Due to reciprocity, absorptivity and emissivity for any particular wavelength are equal at equilibrium – a good absorber is necessarily a good emitter, and a poor absorber is a poor emitter. The temperature determines the wavelength distribution of the electromagnetic radiation.
A metamaterial absorber [1] is a type of metamaterial intended to efficiently absorb electromagnetic radiation such as light. Furthermore, metamaterials are an advance in materials science . Hence, those metamaterials that are designed to be absorbers offer benefits over conventional absorbers such as further miniaturization, wider adaptability ...
With the exception of bare, polished metals, the appearance of a surface to the eye is not a good guide to emissivities near room temperature. For example, white paint absorbs very little visible light. However, at an infrared wavelength of 10×10 −6 metre, paint absorbs light very well, and has a high emissivity. Similarly, pure water ...
Also known as “sundowner’s syndrome,” sundowning is a set of symptoms or behaviors that can be seen in some people with Alzheimer’s disease and dementia, according to the Alzheimer’s ...
In high energy physics experiments, an absorber is a block of material used to absorb some of the energy of an incident particle in an experiment. Absorbers can be made of a variety of materials, depending on the purpose; lead , tungsten and liquid hydrogen are common choices. [ 1 ]
From a glance at his background, one might assume that James F. Slattery would have a difficult time convincing any state in America to entrust him with the supervision of its lawbreaking youth.