akhmeteli
Reputation
10,789
Next privilege 15,000 Rep.
Protect questions
 22h comment What is the electric charge of the Sun and its corona? @honeste_vivere: I am afraid your comment does not address my questions. 1d comment What is the electric charge of the Sun and its corona? @honeste_vivere: Your update does not look very convincing: so the model does not describe dynamic phenomena well, this does not mean it does not describe static phenomena. So what charge does the newer model predicts? So far I just see your conclusions about neutralization. Or is it the authors' conclusion? May 3 comment What is the electric charge of the Sun and its corona? @honeste_vivere: I respectfully disagree with your estimate. An electric field of a point charge $q$ at a distance $r$ is $q/(4\pi\epsilon_0 r^2)$. When I substitute $q=77$, $\epsilon_0=8.85\times 10^{-12}$, $r=7\times 10^8$ (the Sun radius, SI units everywhere), I get $1.4 \mu V/m$. Apr 22 comment Why the tyres of vehicles are always found to be black? @Keepthesemind: Looks like colored tires are produced (doublestartyre.cn/Doublestar/vip_doc/843752.html - the text seems to be machine-translated though) , but it is difficult to find out how to buy them. Apr 20 comment In a waveguide, where does the energy in attenuated waves go? @quantumflash: I believe in this configuration a significant part of EM power is reflected from the waveguide. You decide if you want to call it "losses". In addition, some power is lost in the cable, as it is not perfectly conducting. Apr 19 comment If an object has a temperature, does it have to radiate? @MaxW: "all bodies with a temperature would radiate black body radiation" - maybe I missed something, but this does not seem correct: not all bodies are black bodies, and their radiation may be different from that of a black body. Apr 10 answered Atomic Structure of Liquids! Mar 26 answered Puzzled by a new result on neutrino speeds Mar 25 comment In a waveguide, where does the energy in attenuated waves go? @quantumflash: I am not sure, but I suspect the Poynting flux is oscillating, probably, with a double frequency. There is also a small constant part of the flux related to the losses (and it should be directed towards the walls). Mar 25 comment In a waveguide, where does the energy in attenuated waves go? @Whit3rd: much energy - maybe not, but some energy is always lost, and these losses still provide saturation. Mar 25 comment In a waveguide, where does the energy in attenuated waves go? @quantumflash: Energy is lost in the walls, as they are not perfect conductors (even if they are superconducting, there will be losses at nonzero frequency). Mar 25 comment In a waveguide, where does the energy in attenuated waves go? @quantumflash: You should understand that the exponential attenuation is spatial, not temporal (the amplitude decreases with distance from the source, not with time). With time, the amplitude will increase until saturation ( determined by the balance between energy input from the source and the losses). Mar 25 answered In a waveguide, where does the energy in attenuated waves go? Feb 18 comment Photons can be regarded as particles? Pair production does not necessarily require a massive particle: it can happen in photon-photon collisions (www-spires.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-11581.pdf and references there). Feb 12 comment Why is electric potential scalar? @Ruslan: I have looked at the editing history. Indeed, it was not the OP who put the "electrostatics" tag, it was Qmechanic. The OP initially put the "electromagnetism" tag, so your "tag" argument does not seem quite relevant. Feb 11 comment Why is electric potential scalar? @Ruslan: I did miss that. However, I don't know if it was the OP who put that tag. Feb 11 comment Why is electric potential scalar? @Ruslan: The OP did not mention electrostatics or the rotation group, you read that in her/his question, I did not. Moreover, the OP clearly had some doubts about the electric potential being a scalar, so why should I not tell her/him that there may be some basis for her/his doubts? It also seems that my information was interesting and useful for some other people, so I don't think my answer was a waste of everybody's time.. Feb 3 comment What will be final velocity of three charges $q$, $q$, $2q$? It does not look like they do, so my suggestion looks wrong. Feb 2 answered What will be final velocity of three charges $q$, $q$, $2q$? Feb 2 comment What will be final velocity of three charges $q$, $q$, $2q$? I guess some information on the masses is needed.