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photoelectric effect

(Encyclopedia)photoelectric effect, emission of electrons by substances, especially metals, when light falls on their surfaces. The effect was discovered by H. R. Hertz in 1887. The failure of the classical theory ...

photoelectric cell

(Encyclopedia)CE5 Photoelectric cell: Light causes a photosensitive surface to emit electrons, which flow as current to the positive terminal. A galvanometer measures the current and thus indicates light intensi...

Hall effect

(Encyclopedia)Hall effect, experiment that shows the sign of the charge carriers in a conductor. In 1879 E. H. Hall discovered that when he placed a metal strip carrying a current in a magnetic field, a voltage dif...

greenhouse effect

(Encyclopedia)greenhouse effect: see global warming. ...

Doppler effect

(Encyclopedia)Doppler effect, change in the wavelength (or frequency) of energy in the form of waves, e.g., sound or light, as a result of motion of either the source or the receiver of the waves; the effect is nam...

Compton effect

(Encyclopedia)Compton effect [for A. H. Compton], increase in the wavelengths of X rays and gamma rays when they collide with and are scattered from loosely bound electrons in matter. This effect provides strong ve...

Coriolis effect

(Encyclopedia)Coriolis effect kôrˌē-ōˈlĭs [key] [for G.-G. de Coriolis, a French mathematician], tendency for any moving body on or above the earth's surface, e.g., an ocean current or an artillery round, to ...

Coanda effect

(Encyclopedia)Coanda effect or wall-attachment effect, the tendency of a moving fluid, either liquid or gas, to attach itself to a surface and flow along it. As a fluid moves across a surface a certain amount of fr...