# Find the mean number density of particles in the stellar atmosphere.

## Homework Statement

The atmosphere of a star has a mean radiation pressure of 0.33 N m-2and a mean gas pressure of 8300 N m-2. Calculate:
a) the mean number density of particles in the stellar atmosphere, and
b) the radiation pressure in a stellar atmosphere with twice the eﬀective temperature.

## Homework Equations

$Radiation pressure = \frac{4 \sigma T^{4}}{3c}$ where σ = 5.67*10-8

## The Attempt at a Solution

a) From the radiation pressure equation, I get T=6016K
and I'm not sure where to go from here. I would have thought to have used pV=nRT, but then that bring volume into the equation. I know it's probably really simple and is just something I am forgetting, but I just can't figure it out :/

b) Multiply the given value (0.33) by 16, as it is T4
5.28Pa

Thanks

haruspex
Homework Helper
Gold Member
2020 Award
I would have thought to have used pV=nRT, but then that bring volume into the equation.
You wish to find n/V, right?

:S
Yes I do.
.... I don't even know what to say, how could I not see that?

Thanks