Maxwellian speed distribution

Maxwellian speed distribution

Fig. 3.1 . The Maxwellian probability distribution of speed density (left axis) at different speeds, v (bottom axis) for a temperature of T = 218.85 kelvin and four noble gases, helium (blue), neon (yellow), argon (turquoise) and xenon (purple). The peak of each curve occurs at the most probable speed, vP = (2kT/m)^1/2, where Boltzmannís constant k = 1.38 x 10^-23 Joule per kelvin, T is the temperature, and m is the elementís mass. This distribution was derived by teh Scottish scientist James Clerk Maxwell (1831-1879) in 1873. As indicated in this plot, the peak shifts to higher speeds at lower mass provided the temperature is unchanged, for less massive elements tend to move at faster speeds. A similar change occurs at higher temperatures for a given mass.

Copyright 2010, Professor Kenneth R. Lang, Tufts University