AC voltage from single magnetic pole

[nix85]

Reply to my last posts about Heins and sc at stackexchange.

[verpies]

Wow, you must be a genius. Totally blew my mind.

Glad to know

It was just an example how law can be perceived as violated when it really was not.

Yup, that is why experiments must be designed cleanly to avoid confounding factors.

As usual, you missed the point.
What i referred to was not an experiment.

An empirical measurement proving an expected result, such an Ohm's law, is an experiment, even if it is a small and simple one.

I just linked to a video of perfect 90° phase shift in closed aircore coil.
You claim coil without resistance would have 0 phase shift.
I leave it to you to prove your claim in objective, scientific manner.

I just posted 7 objections to this experiment.
Because of them it cannot be used to draw valid conclusions about the issue at hand.

https://physics.stackexchange.com/questions/179374/is-current-in-superconductors-infinite-if-they-have-0-resistance-then-i-v-r-s
This guy put it nicely...

"In a superconductor, the current can keep flowing "forever" since there is no resistance. But since conductors have inductance (in fact, superconductors are used most often to create magnets like for an MRI scanner), applying a voltage would not (immediately) cause an infinite current to flow".

I agree and this is a scenario in which an external voltage source is applied to an inductive circuit. In other words, the inductor is energized by electric means.

"By turning on a very small (mW) heater, you can locally heat the superconducting loop so it becomes resistive. Now you can apply a voltage to the circuit - and it will preferentially send current around the superconducting part of the loop. The current will not be infinite though - for a given inductance L, the magnet will "ramp" as the current increases according to V=−LdI/dt"

I agree and even have done that feat, but this still is a scenario of the inductor being energized by electric means.


There is second way to energize a shorted superconducting coil. Namely it can be done by magnetic means like this:
1) Insert a permanent magnet into the bore of a coil made out of a an type2 alloy that becomes superconductive when cooled below its critical temperature, when the alloy is hot and not superconductive.
2) The bore is penetrated by the flux of the permanent magnet.
3) The current in the coil is zero
4) Cool that coil below its critical temperature (the coil becomes a superconductor)
5) The permanent magnet's flux penetrating the bore of the sc coil remains constant. It is not expelled as some noobs think.
6) The current in the sc coil is still zero because the flux penetrating it has not changed.
7) Remove the permanent magnet from the bore of the coil. This requires work. Attraction force over distance.
8 ) The sc coil senses the attempted change of flux and generates its own flux that keeps the flux in the bore constant. An ideal shorted coil is a perfect flux clamp.
9) It performs the feat in pt.8 by inducing a current in its winding which generates that flux of the coil.
10) That current circulates "forever" as long as the permanent magnet is kept away from the sc coil.


The current induced in the sc coil appears as fast as you can remove that permanent magnet.  There is no delay.

[verpies]

This test has L1 and L2 reversed.  IOW, L1 is now the current sense winding and L2 is the voltage sense winding.  The inductance of L1 is 143uH and the DCR is .38 ohms.  L1 is wound with 100 turns as stated before and is wound with 15-34 litz wire as is L2.

As one can see, the voltage and current are still in-phase.

So you just neutralized Nix's objection that the number of turns was not like he wanted.
If you want to keep it clean and robust in the future - keep the number of turns the same.

How pure an inductive coil do you desire?  How about giving a desired L/R ratio? 

Good question.


However the issue at hand (described in the 1 BTC challenge) was never restricted to purely inductive circuits, although it includes them, too.
That issue is restricted however, to the energization of the inductive circuit by magnetic means only - not electric means, such as applying energy to it from an external constant voltage PS.

[nix85]

bla bla
An empirical measurement proving an expected result, such an Ohm's law, is an experiment, even if it is a small and simple one.

Experiment in my dictionary means attempt to discover something, working with well known phenomena such as Ohm's law is a routine procedure.

I just posted 7 objections to this experiment.
Because of them it cannot be used to draw valid conclusions about the issue at hand.

You are referring to already "debunked" video.

I agree and this is a scenario in which an external voltage source is applied to an inductive circuit. In other words, the inductor is energized by electric means.
I agree and even have done that feat, but this still is a scenario of the inductor being energized by electric means.


There is second way to energize a shorted superconducting coil. Namely it can be done by magnetic means like this:
1) Insert a permanent magnet into the bore of a coil made out of a an type2 alloy that becomes superconductive when cooled below its critical temperature, when the alloy is hot and not superconductive.
2) The bore is penetrated by the flux of the permanent magnet.
3) The current in the coil is zero
4) Cool that coil below its critical temperature (the coil becomes a superconductor)
5) The permanent magnet's flux penetrating the bore of the sc coil remains constant. It is not expelled as some noobs think.
6) The current in the sc coil is still zero because the flux penetrating it has not changed.
7) Remove the permanent magnet from the bore of the coil. This requires work. Attraction force over distance.
8 ) The sc coil senses the attempted change of flux and generates its own flux that keeps the flux in the bore constant. An ideal shorted coil is a perfect flux clamp.
9) It performs the feat in pt.8 by inducing a current in its winding which generates that flux of the coil.
10) That current circulates "forever" as long as the permanent magnet is kept away from the sc coil.


The current induced in the sc coil appears as fast as you can remove that permanent magnet.  There is no delay.

If you read the second answer on that page you would know it says "The main way current gets started, like in an NMR magnet, is by inductive coupling."

I already quoted the first answer which says current lags voltage due to inductance...

You are going against all of them.. Let's bring in some sc experts here...

Lets see them disperse your fantasies into pixie dust and unicorn farts quicker than Rocky pronounces an intelligible sentence.

[verpies]

Look at the vid i linked.

I just posted 7 objections to this experiment.
Because of them it cannot be used to draw valid conclusions about the issue at hand.


I am repeating this for the sake of members that might not want to read this thread successively/sequentially.

Makes you wonder if phase shift is 90° when he barely pushed it with hand, how much would it be at 1000 or 2000 rpm.

Remember my claim, that there is no phase shift between the induced voltage and induced current in an inductor, which is subjected to external variable flux
...AND that it stays this way regardless of the speed of the flux variations. IOW: it is the same regardless of the speed of the magnet on the rotor.


Also, I claim that the magnitude of the current induced in an ideal shorted coil, does NOT depend on the speed of the flux variations it is subjected to.
IOW: The induced flux does not depend on the speed of the permanent magnet being swept across the shorted ideal coil (or being removed from this coil, or inserted into that coil).