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## Homework Statement

There is a perfectly absorbing spherical shell with radius R

_{1}suspended in space. Inside is a smaller spherical shell with radius R

_{2}. Inside that shell is a ball of radius R

_{3}. All three objects are concentric. In the center of the ball is a point source radiation with power W.

Find the temperatures T

_{1}, T

_{2}, T

_{3}of the outer shell, inner shell, and sphere. The three objects are in thermal equilibrium.

## Homework Equations

W = σT

^{4}(4piR

^{2})

## The Attempt at a Solution

I wondered at first if the temperature of the outer shell

T

_{1}= (W/σ4piR

_{1}

^{2})

^{[itex]\frac{1}{4}[/itex]}

But my question is if the sphere in the middle contribute to the total power received by the outer shell? As in, the sphere emits some power, the inner shell absorbs it and emits some power, and the outer shell soaks up both the power from the sphere and the inner shell?

Then what about the inner shell? Does it get the power from the sphere and the outer shell? Or just the sphere?

what about the sphere? Does its temperature depend just on itself? Or is it rather like the greenhouse effect where the sphere resembles the planet and the shells trap radiation and increase the temperature of the sphere itself?

Help appreciated!