Diffusion equation: time for an element to diffuse at set distance

[jblakes]

Good morning,

I'm trying to workout the time for an element to diffuse at set distance in microns.

I have the distance, the diffusion coefficient, just unsure which equation I actually use.

X= sqrt DT or the other one x= sqrt 2DT.

I can't seem to figure out when you use one and not the other.

Thanks in advance
James

 

[Chestermiller]

Good morning,

I'm trying to workout the time for an element to diffuse at set distance in microns.

I have the distance, the diffusion coefficient, just unsure which equation I actually use.

X= sqrt DT or the other one x= sqrt 2DT.

I can't seem to figure out when you use one and not the other.

Thanks in advance
James

What is the exact situation you are looking at?