ثابت شتفان-بولتسمان

(تم التحويل من Stefan–Boltzmann constant)

ثابت ستيفان-بولتزمان (بالإنگليزية: Stefan–Boltzmann constant) هو ثابت فيزيائي وهو ثابت التناسب في قانون ستيفان - بولتزمان.

The value of the Stefan–Boltzmann constant is given in SI units by

σ = 5.670373(21)×10−8 W m−2 K−4.[1]

In cgs units the Stefan–Boltzmann constant is:

In thermochemistry the Stefan–Boltzmann constant is often expressed in cal cm-2 day-1 K-4:

In US customary units the Stefan–Boltzmann constant is:[2]

The value of the Stefan–Boltzmann constant is derivable as well as experimentally determinable; see Stefan–Boltzmann law for details. It can be defined in terms of the Boltzmann constant as:

where:

The CODATA recommended value is calculated from the measured value of the gas constant:

where:

.. الصيغة ذات الأبعاد : [ M 1 L 0 T -3 K -4]

A related constant is the radiation constant (or radiation density constant) a which is given by:[3]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

الهامش

  1. ^ "CODATA Value: Stefan-Boltzmann constant". The NIST Reference on Constants, Units, and Uncertainty. US National Institute of Standards and Technology. June 2011. Retrieved 2013-11-03. External link in |work= (help)
  2. ^ Heat and Mass Transfer: a Practical Approach, 3rd Ed. Yunus A. Çengel, McGraw Hill, 2007
  3. ^ Radiation constant from ScienceWorld