# At room temperature, the free path of molecules present in air is approximately-

50 views
in Physics
closed
At room temperature, the free path of molecules present in air is approximately-
1. 10-7 /m
2. 10-4 /m
3. 10-10 /m
4. 10-13 /m

by (54.3k points)
selected

Correct Answer - Option 2 : 10-4 /m

Concept:

Mean Free Path (λ):

• The distance travelled by a gas molecule between two successive collisions is known as a free path.
• During two successive collisions, a molecule of gas moves in a straight line with constant velocity.
• The average distance that a particle can travel between two successive collisions with other particles.

$\lambda = \frac{{Total\;distance\;travelled\;by\;a\;gas\;molecule\;between\;successive\;collisions\;\;}}{{Total\;number\;of\;collisions}}$

$\Rightarrow \lambda = \frac{1}{{\sqrt 2 \pi n{d^2}}}$

Where,

n = number of molecules per unit volume and

d = diameter of a molecule