Another quick question...If you take the cavity and put an object in it at a certain temperature, then the body will cool via radiation and a certain flux will emerge from the cavity. If you put a second body, same temp same properties, in the cavity then the flux from the cavity remains the...
Ok...I think it helps me to look at this in terms of the material achieving equilibrium with the field. So when you say our poorly absorbent material, due to mutiple reflections, increases the quantity of radiation to achieve equilibrium with the field I presume this is with respect to our white...
Ok, I assumed that the black body was the limit, and I see that it is driven by the inherent absorption of the material, even if it is vanishingly small. That's where my fundamental issue lies. I presume that if your absorption were zero that would represent the blackbody limit.
I believe I am going down the misleading path. Will try to clarify. Let's take two slabs of gold with the same dimensions radiating into free space considering radiation from one side which has area 2L X 2L . We drill a square hole in one slab to a depth of say of L and sides L X L. So one slab...
Yeah I understand the cavity radiator idea...looked at far too many of them lately. But doesn't that support the idea that there is no difference between the radiative flux from a hole with an aperture X (and some variable depth), and a body (black or non-ideal) with a side of area X?
I guess its what I would expect, but my understanding of the second law say's it should not happen. I've read about miniscule increases in radiation from surface roughening but nothing of any signficance. How would you calculate the increased radiation?
Hi, having a bit of trouble with a basic question on thermal radiation.
If you take a slab of material that has the characteristics of a blackbody and heat it to temperature where its only emitting in the IR, then its temperature will slowly decrease as the heat is rejected (assuming no...