Timeline for Is the magnetic field of a moving electron caused by length contraction in the direction of motion?
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| Apr 13, 2017 at 12:39 | history | edited | CommunityBot |
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| Jan 25, 2017 at 0:56 | history | edited | ProfRob | CC BY-SA 3.0 |
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| Jan 25, 2017 at 0:40 | comment | added | ProfRob | @descheleschilder they would not do so in the laboratory frame either. | |
| Jan 25, 2017 at 0:39 | comment | added | ProfRob | @descheleschilder I don't really understand what you are saying. A magnetic field is not a force. Nor do I understand your question "where does the magnetic field come from?". There is only an electromagnetic field. Electric fields and magnetic fields are not invariant under Lorentz transforms and are frame-dependent quantities. The electrons would not move in parallel unless you compelled them to do so somehow. The force necessary to do so would also be transformed according to special relativity so that if the electrons showed no acceleration along their line of centres in their rest frame, | |
| Jan 25, 2017 at 0:04 | comment | added | Deschele Schilder | @RobJeffries-So the two electrons don't keep moving parallel because from our perspective the force between them gets bigger by a factor 1/$\gamma$? | |
| Jan 24, 2017 at 23:57 | vote | accept | Deschele Schilder | ||
| Jan 24, 2017 at 23:58 | |||||
| Jan 24, 2017 at 23:53 | comment | added | Deschele Schilder | @RobJeffries-So the magnetic field is not the extra force that appears as the electric field density get bigger? What about the term $B=-(\frac{\gamma}{c^2})vXE$? Where does B come from? | |
| Jan 24, 2017 at 23:32 | comment | added | ProfRob | @descheleschilder No, as you can see if you follow the treatment above, the increased repulsion due to the "compressed" electric field lines is countered by the magnetic part of the Lorentz force acting in the opposite direction. Two parallel currents flowing in the same direction attract each other, right? | |
| Jan 24, 2017 at 21:49 | comment | added | Deschele Schilder | @RobJeffries-Is the repulsive force between electrons in the direction perpendicular to their velocities not increased because from our perspective the space in the direction of motion is contracted and so is the density of the electric field lines, which is equivalent to a bigger repulsive force? | |
| Jan 21, 2017 at 12:57 | history | edited | ProfRob | CC BY-SA 3.0 |
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| Jan 21, 2017 at 11:33 | comment | added | ProfRob | @stuffu The repulsive force between the electrons in the direction perpendicular to their velocities, is reduced by a factor of $\gamma$, exactly as demanded by special relativity. | |
| Jan 21, 2017 at 10:16 | comment | added | stuffu | "Therefore, when considered in the stationary frame, the repulsion between the electrons would be much greater than given by Coulomb's law." But actually repulsion is smaller. That's one reason why same currents attract magnetically. | |
| Jan 21, 2017 at 9:41 | history | answered | ProfRob | CC BY-SA 3.0 |