Question

defind mean free path and write down its expression​

Answer 1

Answer:

The mean free path is the distance that a molecule travels between collisions. The mean free path is determined by the criterion that there is one molecule within the "collision tube" that is swept out by a molecular trajectory. The criterion is: λ (N/V) π r2 ≈ 1, where r is the radius of a molecule.

Answer 2

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Mean free path of a molecule is defined as the average distance travelled by the molecule between two successive collisions and it is denoted by λ.

${\huge{\boxed{\tt{\color {black}{λ = \frac{1}{ \sqrt{2} n\pi {d}^{2} } }}}}}$

where n = number of molecules per unit volume

d = diameter of each molecule