Boltzmann constant
The Boltzmann constant (symbol: kB or k) is a physical constant which links energy and temperature on a molecular scale. It also appears in statistical definitions of entropy. It is named after the Austrian physicist Ludwig Boltzmann. The 2006 CODATA recommended value is 1.380 6504(24) × 10−23 J K−1.[1]
Determination
The Boltzmann constant is currently determined from the molar gas constant R
- kB = R/NA
with R being determined from measurements of the speed of sound in argon. The current uncertainty in the value of kB is entirely due to the uncertainty in the value of R: modern measurements may push this below 10−6.[2][3]
Direct methods for determining kB have also been developed recently.
Notes and references
Notes
References
- ↑ Mohr, Peter J.; Taylor, Barry N.; Newell, David B. CODATA Recommended Values of the Fundamental Physical Constants: 2006. Rev. Mod. Phys. 2008, 80 (2), 633–730. doi:10.1103/RevModPhys.80.633, <http://physics.nist.gov/cuu/Constants/codata.pdf>. Direct link to value.
- ↑ Moldover, Michael R. Optimizing acoustic measurements of the Boltzmann constant. C. R. Phys., 10 (9), 815–27. DOI: 10.1016/j.crhy.2009.10.007.
- ↑ Pitre, Laurent; Guianvarc’h, Cécile; Sparasci, Fernando; Guillou, Arnaud; Truong, Daniel; Hermier, Yves; Himbert, Marc E. An improved acoustic method for the determination of the Boltzmann constant at LNE-INM/CNAM. C. R. Phys., 10 (9), 835–48. DOI: 10.1016/j.crhy.2009.11.001.
- ↑ Benz, Samuel; White, D. Rod; Qu, JiFeng; Rogalla, Horst; Tew, Weston Electronic measurement of the Boltzmann constant with a quantum-voltage-calibrated Johnson noise thermometer. C. R. Phys., 10 (9), 849–58. DOI: 10.1016/j.crhy.2009.10.008.
- ↑ Djerroud, Khelifa; Lemarchand, Cyril; Gauguet, Alexandre; Daussy, Christophe; Briaudeau, Stephan; Darquié, Benoît; Lopez, Olivier; Amy-Klein, Anne, et al. Measurement of the Boltzmann constant by the Doppler broadening technique at a 3.8 × 10−5 accuracy level. C. R. Phys., 10 (9), 883–93. DOI: 10.1016/j.crhy.2009.10.020.
Further reading
- Bormashenko, Edward; Sheshnev, Avigdor Measurable Values, Numbers and Fundamental Physcal Constants: Is the Boltzmann Constant kB a Fundamental Physical Constant?. Therm. Sci. 2009, 13 (4), 253–58. DOI: 10.2298/TSCI0904253B.
External links
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See also the corresponding article on Wikipedia. |
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