Timeline for Non-stationary capacitor
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 13, 2017 at 12:39 | history | edited | CommunityBot |
replaced http://physics.stackexchange.com/ with https://physics.stackexchange.com/
|
|
| Sep 14, 2014 at 8:53 | vote | accept | Fabio | ||
| Sep 13, 2014 at 18:00 | comment | added | honeste_vivere | If you want to treat it like an antenna, then the simplest way is to move far enough away (i.e., the radiation zone) from the capacitor so that the system resembles a simple dipole antenna. If you are too close, then you have the complications I mentioned earlier (e.g., fringe fields and the dipole electric fields of the capacitor). I should note that I forgot one of the magnetic field terms (from the wire) in my original answer in the general approach... | |
| Sep 13, 2014 at 10:17 | comment | added | Fabio | That's the answer I was looking for! I'm not practical with radiation, can you give me a hint on how to formalize the problem? (If it's not excessively complex, otherwise I can stop here) | |
| Sep 13, 2014 at 0:16 | comment | added | CuriousOne | One can't neglect these terms. Outside of the capacitor you would have either a finite size loop producing something of a dipole field or an infinite antenna. Unless you are restricting yourself to a special volume, where the problem can be simplified, you would have to solve for the complete radiation field (which, for the infinite antenna, would lead to a divergent radiative power, of course). | |
| Sep 12, 2014 at 16:36 | comment | added | Fabio | Thanks! How can I show that such term may be neglected? | |
| Sep 12, 2014 at 16:32 | comment | added | honeste_vivere | Ah yes, sorry about that. You could look at one plate plus the wire feeding the plate as a system. The wire contributes the typical magnetic field proportional to (I/r) and the plate contributes ~K, both being time-dependent. The electric field would then have two parts, one from the time-varying charge density on the plate (Gauss' law) and one from the time-varying magnetic fields (Faraday's law). If you assume the plates are close enough and large enough, then the latter term will dominate and the former can be neglected. | |
| Sep 12, 2014 at 16:17 | comment | added | Fabio | This is correct but, if I got you right, these are expressions for the electric field inside the capacitor; I was looking for the electric field outside. | |
| Sep 12, 2014 at 16:03 | history | answered | honeste_vivere | CC BY-SA 3.0 |