Explain Thermodynamic Temperature Scale

Thermodynamic Temperature Scale.

Temperature scales to a greater extent than oft than non depend on the thermal expansion of a gas or mercury. Since the coefficients of expansion are non constant over a make of temperature, the scales bear uncertainty. In fellowship to overcome this difficulty, Lord Kelvin suggested the thermodynamic temperature scale which is based upon the efficiency of a reversible machine.

Suppose at that spot are 2 constant temperature oestrus reservoirs as well as a reversible car operates betwixt them, 1 acting every bit source as well as the other every bit the sink. The temperature of each reservoir on the novel scale is as well as then defined every bit " proportional to the quantity of oestrus transferred to or from it inward the reversible cycle". If Q2 is the oestrus transfer inward the at a higher temperature as well as '-Q1' that at a lower temperature; as well as then the respective temperature on the thermodynamic scale is θ2 and θ1, given by

In this way, the ration of the 2 temperature is defined inward a agency independent of nature of whatever detail thermodynamic substance.

 The seat of the aught on the Kelvin scale may travel derived every bit :

Invert equation (i) as well as subtract the number from unity. Thus

and putting θ1 = 0, i.e., aught of the scale, nosotros get

Therefore, aught of the Kelvin scale is the temperature of the sink for a reversible car amongst an efficiency of unity, that is, the car capable of converting oestrus completely into work. It is possible exclusively at the absolute aught on the ideal scale of temperature, it follows that the Kelvin scale as well as the gas scale, are actually the same. Because of this identity, temperatures on the absolute scale, inward which the melting betoken of H2O ice is taken every bit 273.16°, C are referred to every bit degrees Kelvin as well as represented past times K.