Dielectricconstant gas thermometer 
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As a special version of the gas thermometer, the dielectric constant gas thermometer (DCGT) exploits the fact that the permittivity (dielectric constant) ε of an ideal gas of low number density N/V or low pressure p is given by ε = ε_{0} + α_{0}·N/V (α_{0}_{ }being the static dipole polarisability of a single gas atom). The equation of state thus can also be written in the form p = kT(ε  ε_{0})/α_{0} and, analogous to the gas thermometer, T/T_{TPW} = (p/p_{TPW})·(ε_{TPW}ε_{0})/(εε_{0}) is obtained. The DCGT serves to determine εε_{0} by measuring the capacitance variation of a suitable gasfilled capacitor when the gas is pumped off. References

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