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## Homework Statement

Two large plates are parallel and close to each other, vacuum is between them. they are held at 200

^{0}K and 300

^{0}K.

What is the energy transfer rate between them.

## Homework Equations

The energy emission rate per unit area-the Stefan-Boltzmann Law: $$R=\varepsilon\sigma T^4$$

##\varepsilon## is the emissivity of the surface

##\sigma=5.672E-8[w/sec]##

## The Attempt at a Solution

The solution is 368[w/m

^{2}], it's the answer if the emission is of a black body:

##1\cdot 5.672E-8\cdot\left(300^4-200^4\right)=368##

But why don't the emissivities of the surfaces count? what if one surface emits more or less than the other?

In the Stefan-Boltzman formula the outer temperature exists, not the nature of the surrounding surfaces.

I guess it has something to do with the fact that the rest of the radiation, which isn't absorbed, is reflected and comes into account