The mean free path ( \[\lambda\] ) of a gas sample is given by
a) \[\lambda=\sqrt{2\pi\sigma^{2}N}\]
b) \[\lambda=\frac{1}{\sqrt{2}.\pi\sigma^{2}N}\]
c) \[\lambda=\sqrt{2\pi\upsilon\sigma^{2}N}\]
d) None of these

Answer: b
Explanation: Formula for mean free path is \[\lambda=\frac{1}{\sqrt{2}.\pi\sigma^{2}N}\]