Mean Free Path

Ten small planes are flying at a speed of 150 km/h in total darkness in an air space that is 20 × 20 × 1.5 km³ in volume. You are in one of the planes, flying at random within this space with no way of knowing where the other planes are. On the average about how long a time will elapse between near collision with your plane. Assume for this rough computation that a saftey region around the plane can be approximated by a sphere of radius 10 m.

Calculate the mean free path of air molecules at STP. The diameter of N₂ and O₂ is about 3 × 10⁻¹⁰ m

What is the reason for the Brownian motion?

Define mean free path and write down its expression.

Choose the correct option.

The mean free path λ of molecules is given by where n is the number of molecules per unit volume and d is the diameter of the molecules. 

Derive the expression for the mean free path of the gas.

Consider an ideal gas at pressure P, volume V and temperature T. The mean free path for molecules of the gas is L. If the radius of gas molecules, as well as pressure, volume and temperature of the gas are doubled, then the mean free path will be: 

Mean free path of molecules of a gas is inversely proportional to ______.