How is Temperature Measured?
Temperature is the heat of an object, measured by its intensity or degree on a defined scale. There are several scales used to measure temperature, and the most common in use today are Celsius, Fahrenheit, and Kelvin. Note that style guides differ on the use of an upper- or lowercase k for Kelvin. Other temperature scales, which are either little used or obsolete, include Delisle, Newton, Rankine, Réaumur, and Rømer. We’ll review the temperature scales in chronological order, though the Celsius scale underwent changes several hundred years after its initial invention, we’ll save it for last. English scientist Sir Isaac Newton invented the Newton Scale in about 1700. Newton’s temperature scale fixed the degrees by defining the two points of melting snow and boiling water as 0 and 33 respectively. Danish astronomer Ole Christensen Rømer suggested the Rømer temperature scale in 1701, using the set points of the freezing point of brine at 0 and the boiling point of water at 60. A physicist
Stirling engine, Carnot engine Max efficiency of heat engine from temperature ratios – be sure to use Kelvins “You cannot break even” – compare with 1st Law: “You can’t get something for nothing” Entropy of universe always increases Calculate entropy change for thermal equilibrium processes: (constant temperature process) of ΔQ/T Entropy change for melting ice: mL/T
Stirling engine, Carnot engine Max efficiency of heat engine from temperature ratios – be sure to use Kelvins “You cannot break even” – compare with 1st Law: “You can’t get something for nothing” Entropy of universe always increases Calculate entropy change for thermal equilibrium processes: integral of dQ/T The melting ice on table problem.
