M.I.T.-Walter Lewin- Complete Breakdown of Intuition - Part2
Why Physics Stack Exchange recommends it
Physics Stack Exchange answerers and commenters link it when explaining why Kirchhoff's voltage law fails with changing magnetic fields and non-conservative electric fields.
Recommended by 3 people across 3 different months, 2012 to 2023.
What it is
A seven-minute clip from MIT professor Walter Lewin's 8.02 Electricity and Magnetism course (Lecture 16), uploaded to YouTube. He demonstrates that a voltmeter reads different values depending on how its leads are routed around a circuit with a changing magnetic flux, which breaks the usual intuition about voltage.
What people said
Recommends John McAndrew · 2012-06 · Physics Stack Exchange · on “Explaining Walter Lewin's "Complete Breakdown of Intuition"”
The title of your question, it's a "“Complete Breakdown of Intuition”, refers to the reaction of EE and physics professors in Prof Lewin's department at MIT when he performed this experiment in front of them. Four minutes into part2 [this video] : "and some did not believe what they saw"... "some accused me of cheating on the demonstration". The idea of a voltage between two points in a circuit only makes sense when magnetic fields are static because it's independent of the path taken. We can also say the voltage across the terminals of the voltmeter is the same as that across the ends of its leads from Kirchoffs law. In non conservative circuits where there's changing magnetic fields from changi
Recommends user3814483 · 2014-09 · Physics Stack Exchange · on “Application of Kirchhoff's laws in circuits with inductors”
@KyleKanos No, not like that. I'm just trying to remind you not to be so cavalier, and recall that KVL only holds if each and every component is be modeled as a lumped element. Non-conservative fields can create situations where this is not the case. In other words, I'm talking about this: [this video] in case you somehow missed it.
Recommends naturallyInconsistent · 2023-12 · Physics Stack Exchange · on “Confused about sign of mutually induced EMF when applying KVL”
I finally have some time to type this up, and show you how and why KVL is just the wrong way to deal with this. Faraday's Law is, with minus sign as the Lenz's Law, $$\tag1\oint_{\partial S}\vec E\cdot\vec{\mathrm d\ell} =-\frac{\mathrm d\ }{\mathrm dt}\iint_S\vec B\cdot\vec{\mathrm d^2A}$$ Note that the LHS is an integration over the electric field, and the RHS is an integration over the magnetic field. This is a statement of a relationship between two different phenomena, and should be kept as such. Now, let us apply Faraday's Law to the middle circuit. Integrating clockwise starting from the switch, the first contribution is the electric field inside the battery, and we are traversing fro