The temperature of a body may be positive or negative on Celsius and Fahrenheit scales of temperature. The graphs between pressure and temperature in case of different gases are plotted, the graphs indicate that the pressure due to all the gases will become zero at -273.15οC. Lord Kelvin suggested that on a scale of temperature, whose zero coincides with -273.15οC, the temperature of a body will always be positive. Such a scale of temperature is called Absolute scale of temperature and -273.15οC as the zero of this new scale, called absolute zero. It is denoted as 0 K. The ice point (0οC) on the absolute scale corresponds to 273.15K. In general, a temperature of θοC on the absolute scale of temperature is given by:
If C, F and T are values of temperature of a body on Celsius, Fahrenheit and absolute scale of temperature, then
From this equation, it follows that
And F=9/5C+32=9/5(T-273.15) +32.
It may be noted that on temperature scale, a body may have positive or negative value of its temperature but on absolute scale of temperature, the value of temperature of a body is always positive.