Table of Contents

- 1 What do you understand of the mean free path?
- 2 What does mean free path depend on?
- 3 Why mean free path is important?
- 4 What is mean free path find the expression for mean free path?
- 5 How does mean free path depend on number of density of molecules?
- 6 Does mean free path depend on density?
- 7 How is the mean free path of a gas related?
- 8 What is the dependence of the mean free path?

## What do you understand of the mean free path?

mean free path, average distance an object will move between collisions. The actual distance a particle, such as a molecule in a gas, will move before a collision, called free path, cannot generally be given because its calculation would require knowledge of the path of every particle in the region.

### What does mean free path depend on?

From the equation it is observed that the mean free path is directly proportional to the temperature but inversely proportional to the diameter and density of the molecule. From this relation it is understood that the mean free path depends on the diameter, size of the molecule and density of the molecule.

**What is mean free path and how it will be affected with the increase of temperature?**

(a) The mean free path is independent of temperature at constant volume. As the temperature is increased the molecules are moving faster, but the average distance between them is not affected. The mean time between collisions decreases, but the mean distance traveled between collisions remains the same.

**What is the mean free path of a gas molecule on which factors does the mean free path depend?**

Radius of the molecule: As the radius of the molecule increases the space between the molecules decreases causing the number of collisions to increase, thus decreasing the mean free path. Pressure, temperature, and other physical factors also affect the density of the gas and thus affect the mean free path.

## Why mean free path is important?

1.2. The mean free path is the average distance that a particle can travel between two successive collisions with other particles. From Formula 1-11 it can be seen that the mean free path displays linear proportionality to the temperature and inverse proportionality to the pressure and molecular diameter.

### What is mean free path find the expression for mean free path?

The mean free path is the distance that a molecule travels between collisions. The criterion is: λ (N/V) π r2 ≈ 1, where r is the radius of a molecule. …

**Why is mean free path important?**

**What would increase mean free path?**

Factors affecting mean free path Increasing the number of molecules or decreasing the volume causes density to increase.

## How does mean free path depend on number of density of molecules?

Mean free path is inversely proportional to number density of molecules.

### Does mean free path depend on density?

Density: As gas density increases, the molecules become closer to each other. Therefore, they are more likely to run into each other, so the mean free path decreases. Increasing the number of molecules or decreasing the volume causes density to increase. This decreases the mean free path.

**What is mean free path in kinetic theory of gases?**

In the kinetic theory of gases, the mean free path of a particle, such as a molecule, is the average distance the particle travels between collisions with other moving particles.

**Does mean free path increases with pressure?**

If the temperature is increased at constant pressure, the gas expands, the average distance between molecules increases, and the mean free path increases. If the pressure is increased at constant temperature, the gas compresses and the mean free path decreases.

Assuming ideal gas behavior, the mean free path λ between two gas-phase molecules can be related to the temperature T and pressure P within an enclosed system (such as a molecular beam chamber) as follows: (8.1) λ = R T 2 π d 2 N A P where, R is the gas constant, d is the effective diameter of the gas molecule, and NA is Avogadro’s number.

### What is the dependence of the mean free path?

The mean free path has a dependence on the energy distribution of the particles relative to the medium. For particles that can be described by the Maxwellian distribution, 3 such as thermal neutrons in a gas under standard conditions, the mean free path can be computed from (2.1.7) λ m = 1 2 ρ n σ.

**How can the mean free path of a particle be changed?**

It is apparent from these relations that the mean free path of a particle in a gas can be changed by changing the gas temperature and pressure (see example below). The mean free path as defined above depends on the density of the medium.

**What is the mean free path for nuclei?**

The mean free path for collisions of B and C nuclei with nitrogen and oxygen nuclei of the atmosphere and the type of fragmentation occurring in such collisions may be inferred from the observed collision of such nuclei in the glass of photographic plates. Table 1 gives the collision mean free path in glass for A, B, and C nuclei.