The Romer-Lewin ring with inductors (part 3 REBOOT)

Turns out it was easier to redo the video using the intended value of 4kHz and 20 Vpp for the exciting voltage. I added scope measurements for...good measure.
Yes, my sense of humor is stuck in the previous century.
As with all the other videos so far, the purpose here is to show that when a variable magnetic field is present inside the circuit path (the ring with the two inductors) voltage is no longer uniquely defined, and depends on the path.
In this case, it depends on which side of the ring the voltmeter is located or, rather, whether or not the measuring loop (the loop formed by voltmeter, its probes, and the branch of circuit we intend to measure the voltage of ) contains the variable magnetic flux region.
The UT61E voltmeter of the left reads the correct voltage of 19 mV across the branch of circuit containing the smaller inductor. This voltage is equal to the voltage across the opposing branch of the circuit, corrected by the linked EMF.
Conversely, when the UT61E voltmeter is on the right, it reads the correct voltage of 84 mV across the branch of circuit containing the bigger inductor. This voltage is equal to the voltage across the other branch of the circuit, again corrected by the linked EMF.
I used two voltmeters simultaneously connected to the same two points (on the opposite sides of the circuit) to show that the voltages are different at the same time. Unfortunately, only one of my voltmeters is capable of accurately measuring AC voltages at 4kHz; the swapping of the voltmeters serves the purpose of demonstrating that the actual correct voltages are those shown by the fast UT61E (AC voltage measurements up to 5 kHz) while the slower UT139C report values that require a correction.
If I had two fast voltmeters I would have been able to read both correct voltages of 19mV (correct for the left branch) and 84mV (correct for the right branch) at the same time. But such is life. See part 2 in this playlist for further information on this (the frequency behavior of my voltmeters, not the meaning of life).
Lookup "Kirchhoff is for the Birds Lewin" to see a full fledged lecture on what is going on.
UPDATE: The value of 50.5V shown by the UT139C for the branch with the bigger inductor is too far off. I redid the experiment several times off camera and I was unable to reproduce it. The value I get (and also measured in the preview) is 40.64mV, which once correct by multiplication with the 2.02 factor gives 83.7mV, very much in line with the 84mV read by the UT61E and by the oscilloscope.
The value shown in this video, once corrected, amounts to the full EMF of 103mV, so I must have somehow shorted something on the other side of the core.
I will make another video with the correct value reported by both multimeters, and an analysis of the (excellent) agreement with theory and simulation.
Stick around for the LC Lewin ring.

[@freemanrader75]

Looks like a toroidal shaped high frequency transformer or something... What's going on here?

[@copernicofelinis]

Just showing that when a variable magnetic field is present inside the circuit path (the ring with the two inductors) voltage is no longer uniquely defined, and depends on the path.
In this case, it depends on which side of the ring the voltmeter is located.
Lookup "Kirchhoff is for the Birds Lewin" to see a full fledged lecture on what is going on.