<P> The fraction of particles that are not stopped (attenuated) by the slab is called transmission T = I / I 0 = e − x / l (\ displaystyle T = I / I_ (0) = e ^ (- x / \ ell)), where x is equal to the thickness of the slab x = dx . </P> <P> In kinetic theory the mean free path of a particle, such as a molecule, is the average distance the particle travels between collisions with other moving particles . The formula l = (n σ) − 1 (\ displaystyle \ ell = (n \ sigma) ^ (- 1)) still holds for a particle with a high velocity relative to the velocities of an ensemble of identical particles with random locations . If, on the other hand, the velocities of the identical particles have a Maxwell distribution, the following relationship applies: </P> <Dl> <Dd> l = (2 n σ) − 1, (\ displaystyle \ ell = ((\ sqrt (2)) \, n \ sigma) ^ (- 1),) </Dd> </Dl> <Dd> l = (2 n σ) − 1, (\ displaystyle \ ell = ((\ sqrt (2)) \, n \ sigma) ^ (- 1),) </Dd>

What is mean free path of a gas molecule on which factors does the mean free path depend