Rankers Physics

Kinetic Theory of Gases: Practice Problem & Solution

The mean free path $l$ for a gas molecule depends upon diameter, $d$ of the molecule as (2020-Covid)
$l \propto d$
$l \propto d^2$
$l \propto \frac{1}{d}$
$l \propto \frac{1}{d^2}$

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Kinetic Theory of Gases. Understanding the underlying formula is key to arriving at the correct answer below:

The expression for mean free path is $l = \frac{1}{\sqrt{2}\pi n d^2}$. From this formula, it is clear that the mean free path is inversely proportional to the square of the diameter, $l \propto \frac{1}{d^2}$.

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