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You're question is one of the canonical questions that inevitably led to Quantum-Mechanics. It is true that in Classical Mechanics the electron is rotating -> radiating, but if that were true the system would be losing energy all the time, until the electron collapses into the proton. by the same token a proton would be radiating since it also rotates ...


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Let us try to clear up terminology here: A black body is classically defined as a perfect absorber of radiation. No, it is not. The classical description of the perfect absorber also includes an emitter black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. A ...


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It's not necessarily true that most of the photons that strike a wall will be absorbed and turned into heat. The whitest white paints can have a light reflectance value of up to about 85%. There isn't a "wavelength corresponding to white color". An ideal white surface reflects as much as possible of all wavelengths in the visible spectrum. That sounds ...


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1) No, substances almost never completely absorb photons. Otherwise you could not see them. In case a substance would absorb all photons (which is quite hard to achive intentionally) it would be pitch black even if you shine arbitrarily strong light on it (-> black-body). 2) It will be reflected back and forth, but only a finite amount of time. This is ...


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Almost always, when photons hit matter or interact with it, they are not reflected in the way a billiard ball bounces off a billiard table edge. Rather, they are absorbed, the absorber rises into a metastable state, and then a new photon is emitted on the decay of the metastable state. Sometimes, though, when photons undergo an interaction with a lone ...


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It's tempting to think that heat will flow more readily across a cavity from a high emissivity surface to a low emissivity surface than in the opposite direction when the surface temperatures are interchanged, but this is fallacious. The reason is that repeated inter-reflection between the surfaces restores symmetry. Call the radiant flux across the cavity ...


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If we assume that both the aluminum foil and the paint have scalar heat conductivities then their composite will also be scalar, and thus symmetrical. Being both material either poly-crystalline or amorphous this is probably reasonable assumption. @Floris suggested that I expand on this, but not being my area I can only summarize a few ideas from ...


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The second law of thermodynamics forbids materials that conduct better in one (forward) direction than the reverse direction - such a material placed between two containers at thermal equilibrium would drive the temperature away from equilibrium, decreasing the entropy of the whole system and paving the way for a perpetuum mobile... Reflectance and ...


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The main problem with your approach is that you are using the wrong area for the radiation "window". The area over which the exchange of radiative energy can take place is just the window in the door - the walls "see each other" and that part of the radiation has no net effect. So you want to use just $H\cdot W$ for the area. Secondly the window is ...


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OK, I think I've got it, thanks to your comments above as well as this link, which shows how to calculate the temperature of a solar oven. (My situation is very similar to a solar oven, except that the power dumped inside the craft is electrical -- but watts are watts, right?) So, I believe that what I need to do is: Calculate the steady-state ...


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You can combat that the same way we avoid getting too cold: apply insulation. The outer surface of the spacecraft may be very cold, but that doesn't mean the internal temperature is that cold. That is what the greenhouse effect does-it insulates the surface from space. Power dissipated inside the body all becomes heat. If you have solar arrays making ...


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Interesting and complicated question. The things to consider: "Black body radiation" assumes perfect absorption / radiation at all wavelengths. The greenhouse effect comes about from having absorption in the IR: the hot (short wavelength) radiation from the sun can penetrate the atmosphere, but the cooler earth radiates at a lower temperature - longer ...


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Instead of the expansion of the bulb which should be slight, it might also be the air in the thermometer. According to wikipedia, it is filled with nitrogen or air at lower than 1 atm. When we compare this small mass of gas with the "large" mass of mercury, it will most likely heat up faster even with regards to heat capacities. At room temperature, most ...


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When charge accelerates, it radiates energy. The "prototypical scenario" illustating this is the uniformly accelerated point charge and the Larmor Formula (see Wikipedia page of this name) that quantifies the radiated power (both the non-relativistic and relativistic versions are given on the Wiki page). For an everyday example, you can think of a dipole ...


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If you coat the inside, the metal will get hot and this heat will conduct into the building. If you coat the outside (assuming it remains clean…) you will never get hot to begin with. I think this means that case 2 will be better for you. I have often wondered about simply having a secondary roof with a standoff - in essence, a space where air can flow ...


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I am going to address only your second point: It seems that the maximum temperature an object could have is when: B) When the speed of the electrons nears the speed of light. In fact this does not impose any limit to temperature. When you add more and more heat to a body, its atoms and molecules move faster. At this stage, the electrons are not ...


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The entire premise of this question is false, neither do electrons orbit atoms with a well-defined speed, nor does this, in any way, correspond to the temperature, since that is a property of systems in thermal equilibrium, not of single particles. Also, whether the Planck length signifies really a shortest achievable wavelength is...debatable.


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First, a comment. Radiative heat transfer is oftentimes a non-factor for everyday objects encountered here on Earth. Radiative transfer is important for objects that can't exchange heat conductively or convectively, and for objects whose temperatures differ by a marked amount. That said, the rest of this answer will focus on radiative heat transfer. If ...


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A cold object heats up because at any given frequency it emits less energy and receives more energy than a hotter object. In other words, at any given frequency an object is just as efficient an emitter as it is an absorber (with a black body being the most efficient), but hot objects emit more radiation than cold objects do at each frequency, so the ...


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The premise is true if the object is in thermal equilibrium. See, for example, this Wikipedia article. Besides radiation, heat can be transferred by conduction and convection.



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