Mean Free Path
| Formula / Notation | λ = 1/(√2 × π × d² × n) |
|---|---|
| Also Known As | Free path length, collision mean free path, molecular mean free path |
What is Mean Free Path?
The mean free path is the average distance a particle (molecule, electron, photon) travels between successive collisions with other particles. In gases, it depends on the size of the molecules and their number density. At standard conditions, the mean free path of air molecules is about 68 nm. Mean free path is important in kinetic theory, vacuum technology, and transport phenomena.
Formula & Notation
Other Names / Synonyms: Free path length, collision mean free path, molecular mean free path
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
The mean free path is the average distance a particle (molecule, electron, photon) travels between successive collisions with other particles. In gases, it depends on the size of the molecules and their number density. At standard conditions, the mean free path of air molecules is about 68 nm. Mean free path is important in kinetic theory, vacuum technology, and transport phenomena.
Vacuum technology (molecular flow vs viscous flow regimes). Semiconductor manufacturing (thin film deposition). Gas-phase chemistry calculations. Neutron moderation in nuclear reactors. Radiation transport calculations. Atmospheric physics. Ion mobility spectrometry.
Theoretical concept — no direct safety concerns. Vacuum systems where mean free path relevant may have implosion hazards.
The formula or notation for Mean Free Path is: λ = 1/(√2 × π × d² × n)