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## Homework Statement

A gas effuses into a vacuum though a small hole of area [tex]A[/tex]. Show that if the particles effused into an evacuated sphere and the particles condensed where they collided that there would be a uniform coating. (7.6 of Blundell and Blundell)

## Homework Equations

Angular probability distribution. The probability a particle is travelling between [tex]\theta[/tex] and [tex]\theta+d\theta[/tex] to the normal of the small hole.

$$

cos\theta sin\theta d\theta

$$

Surface area of a ring defined on the surface of a sphere with radius of unity where the angles go from [tex]\theta[/tex] to [tex]\theta+d\theta[/tex]

$$

2\pi sin\theta d\theta

$$

## The Attempt at a Solution

Surely it would just be amount of particles over area which is proportional to [tex]cos\theta[/tex]. This is clearly not uniform