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The Fresnel equations (or Fresnel conditions) describe the behaviour of light when moving between media of differing refractive indices. The reflection of ... more

In physics, attenuation (in some contexts also called extinction) is the gradual loss in intensity of any kind of flux through a medium. For instance, dark ... more

The Fresnel equations (or Fresnel conditions) describe the behaviour of light when moving between media of differing refractive indices. The reflection of ... more

The speed of light in vacuum is the speed at which all massless particles and changes of the associated fields (including electromagnetic radiation such as ... 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

The inverse-square law, in physics, is any physical law stating that a specified physical quantity or intensity is inversely proportional to the square of ... more

A horn antenna or microwave horn is an antenna that consists of a flaring metal waveguide shaped like a horn to direct radio waves in a beam. Horns are ... more

When an electromagnetic wave travels through a medium in which it gets attenuated (this is called an “opaque” or “attenuating” ... more

The spectral exitance of a real surface around a given frequency or wavelength, according to the Lambert’s cosine law and the Planck’s law, is ... more

Balmer noticed that a single number had a relation to every line in the hydrogen spectrum that was in the visible light region. That number was 364.50682 ... more