- #1
jjmclell
- 1
- 0
Hi there,
I'm trying to wrap my head around Fick's first law of diffusion (for one dimension):
[tex]J_{x} = -D \frac{\partial \phi}{\partial x}[/tex]
I understand that [tex]\phi[/tex] is the concentration in units amount/volume and that [tex]x[/tex] is position on the gradient in units length. What I don't understand is why [tex]-D[/tex] is in units area/time. If we're talking one dimensional diffusion, why do we bring area into the equation? Or, put another way, why do we square length in the diffusion coefficient?
Thanks,
jjmclell
I'm trying to wrap my head around Fick's first law of diffusion (for one dimension):
[tex]J_{x} = -D \frac{\partial \phi}{\partial x}[/tex]
I understand that [tex]\phi[/tex] is the concentration in units amount/volume and that [tex]x[/tex] is position on the gradient in units length. What I don't understand is why [tex]-D[/tex] is in units area/time. If we're talking one dimensional diffusion, why do we bring area into the equation? Or, put another way, why do we square length in the diffusion coefficient?
Thanks,
jjmclell