We all wonder what Kelvin scale is? or why we use it? Well it's a temperature measured in Kelvin (K). In Kelvin scale the water freezes at 273 K and it boils at 373 K. The Kelvin Scale was invented by a British inventor and scientist name Lord Kelvin (William Thompson, 1824-1907).He also invented about over 50 devices, discovered the second law of Thermodynamics. We use Kelvin scale when it becomes really really cold, like when temperature comes to absolute zero. We always use Kelvin scale when the temperature is at Absolute Zero. Absolute Zero is a point where all the oscillations are the slowest they ever can be, at absolute zero the temperature falls at 0 K.
In 1948, the term dynamical studies of Lord William Thompson Kelvin led him to propose on an absolute Scale of temperature. It was based on his studies of theory of heat, in particular the theory proposed by Sadi Carnot and later developed by Capeyron. The Kelvin absolute temperature scale, as it is now known, was defined much later after conservation of energy had become better understood. We know that temperature is a measure of the average kinetic energy of particles of matter. Gases consist of large numbers of molecules that are in continuous random motion. The average kinetic energy of the molecules does not change with time, and it's proportional to absolute temperature. At any given temperature, the molecules of all gases have the same temperature. The average kinetic energy for the collection of gas molecules in one sample is equal to the average kinetic energy for the collection of gas molecules in the other sample. The molecules in a gas have an average kinetic energy, an individual molecules move at various speeds, (as shown on next page.). The higher the temperature is the greater fractions of the Molecules are moving at higher speed. The pressure of a gas is caused by collisions of the molecules with the walls of container and the magnitude of a pressure is .