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Thermionic emission is the thermally induced flow of charge carriers from a surface or over a potential-energy barrier. This occurs because the thermal ... more

Planck’s law describes the electromagnetic radiation emitted from a black body at a certain temperature. Radiance and spectral radiance are measures ... more

Electrons can only gain and lose energy by jumping from one allowed orbit to another, absorbing or emitting electromagnetic radiation with a frequency ... more

Doppler Effect is the change in frequency and wavelength of a wave for an observer moving relative to the source of the waves. Compared to the emitted ... more

Doppler Effect is the change in frequency and wavelength of a wave for an observer moving relative to the source of the waves. Compared to the emitted ... more

The highest angular resolutions can be achieved by arrays of telescopes called astronomical interferometers: These instruments can achieve angular ... more

Doppler Effect is the change in frequency and wavelength of a wave for an observer moving relative to the source of the waves.Compared to the emitted ... more

Doppler Effect is the change in frequency and wavelength of a wave for an observer moving relative to the source of the waves.Compared to the emitted ... more

In the physical sciences, the wavenumber (also wave number) is the spatial frequency of a wave, either in cycles per unit distance or radians per unit ... more

In radiometry, radiant exitance is the radiant flux emitted by a surface per unit area, and spectral exitance is the radiant exitance of a surface per unit ... more