Absolute Temperature Scale (English System - Rankine Scale)

In our earlier discussion, we mentioned that temperature of a body represents the energy content of the individual molecules. As we heat them, the energy content goes up, and the temperature rises.

Similarly when we cool a body (and thus its molecules), the energy content is reduced and the temperature drops. What will happen if we keep on cooling a substance, to the point where the energy content of the molecules is zero. Obviously, if the energy content is zero, it cannot be reduced any further, therefore this condition must reflect absolute zero temperature.

We can show absolute zero in the two systems. In the English system it is called the Rankine scale and in the SI system it is called the Kelvin scale.

In the Rankine scale, the zero point shows the absolute zero temperature – temperature cannot go below this number – since no energy is left in the molecules. The Rankine Scale is shown on the left hand side of the thermometer shown here. Note that, on the Rankine scale, the freezing point of water is given as 492 deg R, and the boiling point of water is given as 672 deg R.

In the Fahrenheit scale the lowest possible temperature is minus 492 deg F.