Question

Mean free path in kinetic theory can be written as: ( every symbol has standard meaning)

• A. $l=\frac{\mu }{2p}\sqrt{\frac{\pi K_{B}T}{m}}$
• B. $l=\frac{\mu }{2p}\sqrt{\frac{3\pi K_{B}T}{2m}}$
• C. $l=\frac{\mu }{p}\sqrt{\frac{\pi K_{B}T}{2m}}$
• D. $l=\frac{3\mu }{2p}\sqrt{\frac{\pi K_{B}T}{2m}}$

Answer 1

Answer: (C)

$l=\frac{\mu }{p}\sqrt{\frac{\pi K_{B}T}{2m}}$

The mean free path is the average distance traveled by a moving particle (such as an atom , a molecule, a photon) between successive impacts (collisions), which modify its direction or energy or other particle properties.

Mathematically it is expressed as:

$l=\frac{\mu }{p}\sqrt{\frac{\pi k_{B}T}{2m}}$

where, $\mu$ is the viscosity

$m$ is the molecular mass

$p$ is the pressure