Skip to main content
11 votes
Accepted

Trouble understanding the classic approximation of a black body as a hole on a cavity

My professor's notes state that the environmental radiation that enters it is almost imposible to get back out of the cavity That is a little strange formulation, as if somebody would want to get the ...
Ján Lalinský's user avatar
8 votes
Accepted

Should I hold a baby formula bottle to cool it down faster?

Sure! I think I'm qualified to answer, not because I used to teach heat transfer in a Chemical Engineering course, but because I raised four daughters!! Air is an excellent thermal insulator. If you ...
Alfredo Maranca's user avatar
4 votes

Trouble understanding the classic approximation of a black body as a hole on a cavity

I think the answer by @JánLalinský is a good one. I do not intend to contradict it, but I think that the question is answered (at least partially) by clarifying certain points about black body, black ...
Roger V.'s user avatar
  • 60.3k
3 votes
Accepted

Cooling properties of trees and thermal radiation

One needs to distinguish between real temperature and percieved temperature. The temperature we feel can be very different from the actual temperature of the surrounding air depending on factors such ...
paulina's user avatar
  • 1,897
3 votes

Surely $\rm CO_2$ reflects incoming solar infrared radiation?

Most of the incoming solar radiation is in the visible, where CO$_2$ is transparent. The radiation is absorbed by the ground and warms it. The ground radiates in the infrared. Without CO$_2$, the ...
mmesser314's user avatar
  • 41.1k
2 votes
Accepted

Thermal spectrum of a warmer body in a colder room

Suppose I had a piece of glass (just as an example) at room temperature, let's say T0=293 K, and I moved it into a dark room that was TR=1 K. I assume the glass will radiate heat until it and the room ...
Roger V.'s user avatar
  • 60.3k
2 votes

Determine thermal emissivity of material

Some IR thermometric probes have an adjustment for the emissivity of the surface you want to measure the temperature of. What you do then is heat that surface to a known temperature (measured by some ...
niels nielsen's user avatar
1 vote
Accepted

Two interacting blackbodies (one inside another) - when will thermal equilibrium be attained?

Here, the power emitted by $A$, $P_A$, is equal to the power supplied by the fusion reaction. Here is the mistake. In equilibrium the power emitted by $A$ is given by $P_{in}=P_{out}$, and the $P_{in}...
Dale's user avatar
  • 103k
1 vote

Surely $\rm CO_2$ reflects incoming solar infrared radiation?

Is the greenhouse effect not cancelled out by the $\rm CO_2$ in the atmosphere reflecting solar infrared radiation back into space? No. The idea that the greenhouse effect is caused and controlled by ...
Nullius in Verba's user avatar
1 vote

Regarding the absorption property of a blackbody

Let us say that $T_b < T_c$. What will happen is that the central object will radiate less energy than it absorbs until it comes to a new equilibrium at some intermediate temperature. At the same ...
ProfRob's user avatar
  • 133k
1 vote

Regarding the absorption property of a blackbody

how is it able to absorb according to the same law by which it radiates? It must absorb according to the same law by which it radiates according to the second law of thermodynamics. Suppose that a ...
Dale's user avatar
  • 103k
1 vote

Cooling properties of trees and thermal radiation

The question you asked, about the difference in temperature between shady and sunny areas, is not the same as the question of whether trees have cooling benefits. Planting trees may cool the air. ...
anon's user avatar
  • 1,255
1 vote

Should I hold a baby formula bottle to cool it down faster?

Liquid cooling is generally more efficient than air cooling for CPUs and car engines, even though a fan is used in the air cooling versions. In the case of the baby bottle we are not comparing the ...
KDP's user avatar
  • 6,044
1 vote

Should I hold a baby formula bottle to cool it down faster?

Premise and suggestions Before answering your question, I'd like to do again the premise that this question and the comments in your question make from little to no sense to me. Anyway, beside the ...
basics's user avatar
  • 10.7k

Only top scored, non community-wiki answers of a minimum length are eligible