Temperature Thermal Equilibrium Temperature Scale Practical Thermometers Temperature

Temperature Thermal Equilibrium Temperature Scale Practical Thermometers

Temperature

Thermal Equilibrium Zeroth Law of Thermodynamics

Heat l Energy transferred due to temperature difference ¡Energy on the move ¡From high to low temperature l Heat vs. Temperature

Making a thermometer l Thermometric Properties ¡Length ¡Resistance ¡Pressure ¡Voltage

Temperature Scales l Celsius Scale ¡ Ice point, 0 ¡ Steam point, 100 ¡ 100 divisions in between , hence a. k. a. centigrade scale ¡ Unit: degree Celsius, C l Fahrenheit Scale ¡ Ice point, 32 ¡ Steam point, 212 ¡ 180 divisions in between ice point and steam point ¡ Unit: F

Thermodynamic Scale l Absolute zero, 0 l Triple point of water, 273. 15 l 100 divisions in between ice point and steam point l This scale does not depend on the property of any particular substance l a. k. a absolute scale l Conversion: K = C + 273. 15

Types of Thermometer l Liquid-in-glass ¡ Length of liquid thread ¡ Convenient, portable ¡ Fragile, limited range ¡ (234 -723 K)(IPTS) l Constant Volume Gas Thermometer ¡ Pressure of a fixed mass of gas ¡ Wide range, accurate ¡ Bulky, inconvenient, slow to respond ¡ Below 90 K

Types of Thermometer l Resistance ¡ Electrical resistance of platinum coil ¡ Wide range, accurate ¡ Best type for small temp differences ¡ Slow to respond ¡ 90 -903 K l Thermocouple ¡ emf across junctions of 2 dissimilar metals ¡ Fast response, wide range ¡ Can be stored ¡ For accuracy, high resistance millivoltmeter must be used ¡ 903 -1336 K

Types of Thermometer l Pyrometer ¡Color of thermal radiation from hot object ¡No contact with hot object ¡Can be portable ¡Not highly accurate ¡Above 1336 K

The End