The Knudsen number is equal to this value divided by a characteristic length.
Spectrum hardening causes this quantity to change with distance. When particles have a Maxwell distribution, the formula for this quantity contains a coefficient of the square root of 2 divided by 2, and in a gamma-ray source this quantity is the reciprocal of the attenuation coefficient. The Knudsen number is equal to this value divided by a characteristic length. Commonly used to estimate a molecule's size, it is naively defined as one over the cross-sectional area times the number of particles. Directly proportional to temperature and inversely proportional to diameter, for 10 points, name this value useful in the kinetic theory of gases, the average length which a particle can travel without hitting something.
Spectrum hardening causes this quantity to change with distance.
{Mean free path}