- #1
Selveste
- 7
- 0
Homework Statement
An initial particle distribution n(r, t) is distributed along an infinite line along the [itex]z[/itex]-axis in a coordinate system. The particle distribution is let go and spreads out from this line.
[itex] a) [/itex] How likely is it to find a particle on a circle with distance [itex]r[/itex] from the [itex]z[/itex]-axis at the time [itex]t[/itex]?
[itex]b)[/itex] What is the most likely distance [itex]r[/itex] from origo to find a particle at the time [itex]t[/itex]?
Homework Equations
The diffusion equation is given by
[tex] \frac{\partial n}{\partial t} = D \nabla^2 n [/tex]
where [itex] \nabla^2 [/itex] is the laplace-operator, [itex] D [/itex] is the diffusion constant and [itex] n [/itex] is the particle density.
The Attempt at a Solution
[/B]
I take it by "line along the z-axis" they mean ON the z-axis(?).
a) I am not sure how to go about this. Would it involve a Fourier transform, or can it be done more easily? Any help on where/how to start would be appreciated.
b) The most likely distance from the z-axis would be zero, because of symmetry(?). So the distance from origo would be z.
Thanks.