\[L=\sqrt{2Dt}\]
Variables
Ldiffusion length (m)
Ddiffusion coefficient (m²/s)
tdiffusion time (s)
Description
What is this formula?
The diffusion length formula calculates the average characteristic distance traveled by particles undergoing diffusion during a given time interval.
When to use it
Use this formula in chemical physics, material science, semiconductor physics, and transport phenomena when estimating how far molecules, atoms, ions, or particles spread by diffusion.
Example
A gas molecule diffuses in air with a diffusion coefficient of 1.5×10^-5 m²/s for 120 seconds.
Data:
D = 1.5×10^-5 m²/s
t = 120 s
Formula:
L = √(2Dt)
Substitution:
L = √(2 × 1.5×10^-5 × 120)
Result:
L ≈ 0.060 m
The average diffusion length is approximately 6.0 cm.
Applications
- Gas diffusion studies
- Semiconductor carrier transport
- Heat and mass transfer
- Molecular transport analysis
- Chemical reactor design