Physical constant

Uncommon card · No. 184148

A physical constant is a non-varying quantity that appears in a theory or model of some physical phenomena. Some physical constants appear in models of fundamental phenomena and impact many parts of physics. These constants include the speed of light in vacuum c, the gravitational constant G, the Planck constant h, the electric constant ε0, and the elementary charge e for examples. Tables of the numerical value of these fundamental physical constants or universal constants are carefully maintained and widely consulted. Some physical constants are coefficients or parameters assumed to be constant in specialized models without being universal constants. Examples include the characteristic time, characteristic length, or characteristic number (dimensionless) of a given system, or material constants (e.g., Madelung constant, electrical resistivity, and heat capacity) of a particular material or substance. Physical constants cannot be explained by the theory that incorporates them but their...

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