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Working Of Electrical Resistance Thermometer



 In the  resistance thermometer the change in resistance of a metal wire due to its change in temperature is the thermometric property. The wire, frequently platinum, may be incorporated in a wheat stone bridge Circuit. The platinum resistance thermometer measures temperature to a high degree of accuracy and sensitivity, which makes it suitable as a  standard for the calibration of other thermometers.

In a restricted range, the following quadratic equation is often used :

                                  R=R0 (1 + At + Bt2) 

where R0 is the resistance of  the platinum wire when it is surrounded by melting ice and A and B are constants. 

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