The Romer-Lewin ring with capacitors (part 3)
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- Опубліковано 22 сер 2024
- Before I turn to the ring with inductors, I wanted to show the voltmeters' readings on the capacitive Romer-Lewin ring.
This is the same ring that has been used in the previous two videos, and we can clearly see that even with capacitors the voltage across the very same two points is different, depending on which capacitor is part of the measurement loop that does not include the variable magnetic flux.
Resist the temptation to conclude this is a probing or measurement issue because it is not that. The vtages are different in the two branches of the ring itself irregardless of the presence of the probes and voltmeters.
I wanted to show how close the measurement are to the values predicted by theory (this is due to the large values of reactances, compared to the ESR of the capacitors), and also stress the fact that the shape of the measurement loops (the loops formed by voltmeter, its probes, and the portion of circuit between them, on the voltmeter's side) does not affect the measurements at all.
Spoiler alert: the gray winding I added to the toroidal core will be used to create a faster changing magnetic field in the experiments with the inductive ring.
But first I need to solve my problem with video size: a minute and a half of video at the smallest resolution my phone allows required an upload of 120 MB.
wow nice
@ Copernico Felinis
There is no magnetic field in the vicinity of the Voltmeter wires but there is an induced electric field from the solenoid along the voltmeter wires. It causes induction of current to take place at the location of the voltmeter wires and that electric field is present along with the coulomb field originating from around the ring with the capacitors. So the Voltmeters readings are in agreement with the voltages across the capacitors.
That is correct.
If you allow me some nitpicking, what is important is that there be no appreciable variable magnetic field *linked* by the measuring loop. There is a changing magnetic field 'in the vicinity' because the core is in the vicinity' of the probes, but the loop formed by voltmeter, probes and 'nearest capacitor' does not link any of it. That is where one CAN APPLY KVL.
Notice that each voltmeter can be seen as part of two measurement loops: one is that described above, the other is the loop formed with the 'farthest' capacitor. This second loop, though, does link the variable magnetic field in the core and KVL does not apply. One needs to use Faraday's law to recover the correct voltage across the farthest branch of the ring.