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#562 – Electroboom!

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thinkfat:

--- Quote from: ogden on January 13, 2022, 11:08:20 pm ---
--- Quote from: Sredni on January 13, 2022, 10:41:12 pm ---In my world they are all identical and zero, if we use perfect conductors. In the real world they are equal to the current flowing in the ring times the resistance of the length of the arc, whatever that maybe. I can easily calculate their value no matter how the ring is shaped and placed.

--- End quote ---

Engineer just measured 12VAC on transformer output. Wannabe scientist: as resistance of transformer secondary winding is zero, then voltage on terminals of transformer secondary is I*R meaning - zero. [edit] Those guys claim to know Faraday's law? C'mon.

--- End quote ---

Dumb Engineer doesn't want to care about what's happening inside the transformer. He just measures across the transformer terminals and is happy. Engineer who knows Faradays Law understands why his measurements are sometimes giving unintuitive results. This is also the Engineer who's designs pass EMC testing.

Siwastaja:

--- Quote from: thinkfat on January 14, 2022, 07:35:34 am ---This is also the Engineer who's designs pass EMC testing.

--- End quote ---

Yeah. And EMC is still quite manageable; the mediocre engineer who only knows Kirchoff laws, will be able to try the 5-10 most commonly known "rules of thumb" of EMC design, and likely gets a pass. They don't calculate or simulate EMC; just experimental improvements, until emissions are below the threshold.

Similarly to modifying the layout and probe wiring until the results match within 2%, but with the difference that emissions do not need to match within 2%, getting under the bar is enough.

But then, try to design a modern-day radio communication device. Not a pre-certified module, the full design. Now you just can't avoid understanding the physics anymore.

And to be fair, I can't do it. But I'm grateful to those who can.

Sredni:

--- Quote from: jesuscf on January 14, 2022, 06:26:59 am ---
--- Quote from: Sredni on January 13, 2022, 10:41:12 pm ---In my world they are all identical and zero, if we use perfect conductors. In the real world they are equal to the current flowing in the ring times the resistance of the length of the arc, whatever that maybe. I can easily calculate their value no matter how the ring is shaped and placed.

--- End quote ---

I see.  I have nothing to discuss with you then.

--- End quote ---

This is a common trait of you KVLers: when you are faced with your self-contradictions you either censor your critics (like fromjesse, RSD Academy on their channels, where they can be censors) or all of a sudden you just find out there are other, more important thing to do and flee (like Jesse Gordon here, where he has no power to censor critics, or Mabilde on his channel, or you now). Except they always find the time to answer the easy question or starting from zero, ignoring all the inconsistencies that made em stop discussing with the other critics.

Anyway, you mentioned the magnetic potential. Hayt calls the scalar magnetic potential Vm and look what he has to say about it (this is from my fourth edition, but I am pretty sure you can find it on one of the editions you have at hand):





Oh, look: in the electrostatics case, the voltage is also scalar electric potential difference and as such is independent of path (thanks to that circulation equal to zero). In the magnetostatic case, on the other hand, the fact that the corresponding circulation is NOT zero, but I, the magnetic scalar potential ends up being a non-conservative field. The path integral becomes path-dependent and multivalued: to get the actual value YOU NEED TO SPECIFY THE PATH FROM a TO b.

And now look what happens to the electric potential in the presence of a changing magnetic flux:



Oh, look! The circulation of the electric field that in the electrostatic case was zero is now equal to -d flux/dt, and this - just like in the case of the scalar magnetic potential - makes the integral (voltage) multivalued and path dependent. YOU NEED TO SPECIFY THE PATH FROM a TO b.

This is written on the book you have what? five copies of?

ogden:

--- Quote from: thinkfat on January 14, 2022, 07:35:34 am ---Dumb Engineer doesn't want to care about what's happening inside the transformer. He just measures across the transformer terminals and is happy. Engineer who knows Faradays Law understands why his measurements are sometimes giving unintuitive results. This is also the Engineer who's designs pass EMC testing.

--- End quote ---

It does not matter - he is dumb engineer or dumb scientist. If he do not use proper model for analysis, he do not get proper results. Problem with all this engineers vs scientists tribe war is - both tribes do not even agree about common model which will be used for analysis. Scientist tribe say that segment of the loop can't be "lumped element" because "we say so". Engineers who say that EMF is induced in any kind of conductor, not necessarily loop - are labelled with swear words. Go figure.

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