In electric resistance thermometer, the thermometric property is

In electric resistance thermometer, the thermometric property is

a. electric current passing through a metal wire
b. resistance of a metal wire
c. voltage between two extreme end points of a metal wire
d. none of the above

Correct Answer : b. resistance of a metal wire

Explanation :

When current passes through a metal wire, as the temperature increases the resistance increases due to vibration of molecules in metal and collision of electrons carrying current. Therefore resistance of a metal wire is taken as a thermometric property in electric resistance thermometer. A suitable wire may be used for measuring temperature and the setup is arranged in a Wheatstone bridge circuit. Usually platinum wire is used as it can measures temperature to a high degree of accuracy and sensitivity. Platinum makes electric resistance thermometer suitable for the calibration of other thermometers.