# Motional EMF

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12 minutes ago, iNow said:

Where specifically, amd what does it say there? Will you please repeat it here for convenience?

The intent was a call for help debarking my experiment on Lorentz force and I got response, thank you...

Since no one has suggested experimental setup which would show Motional EMF I have concluded that Lorentz force equation is defective or false... Base on that I wrote my own paper where I claim the new force with correct equations, mathematical simulation in Matlab and links to current classroom reference...

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It was a straight forward request. You provided a crooked response.

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2 hours ago, icester said:

I never said "I do not have wire moving trough magnetic field"... I've said that there is no EMF when wire moves with constant velocity trough constant magnetic field ...

Which is wrong. You can have an EMF, with the correct motion.

The voltage is proportional to the change in flux per unit time. When you rotate the magnet, the flux of the enclosed area does not change. Thus, no voltage.

13 minutes ago, icester said:

The intent was a call for help debarking my experiment on Lorentz force and I got response, thank you...

Since no one has suggested experimental setup which would show Motional EMF I have concluded that Lorentz force equation is defective or false... Base on that I wrote my own paper where I claim the new force with correct equations, mathematical simulation in Matlab and links to current classroom reference...

Um, what? There have been a number of them, including textbook diagrams showing how to do it. You are using a different setup with your rotating magnet. Why would you expect the same results with a different setup?

5 hours ago, icester said:

If you read the thread carefully you will find out that Lorentz claimed otherwise. You do get voltage proportional to the velocity of charge particle moving in uniform magnetic field... There is even online calculator where the apparent Motional EMF can be calculated: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/genwir3.html#c1

Do you recognize that the experiment shown in the diagram in that link does not represent the experiment you have described?

When one fails to replicate the results that others have done thousands if not millions of times, it take quite a lot of chutzpah to conclude the physics is flawed.

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5 minutes ago, swansont said:

Which is wrong. You can have an EMF, with the correct motion.

The voltage is proportional to the change in flux per unit time. When you rotate the magnet, the flux of the enclosed area does not change. Thus, no voltage.

Um, what? There have been a number of them, including textbook diagrams showing how to do it. You are using a different setup with your rotating magnet. Why would you expect the same results with a different setup?

OK, please provide an example of correct setup...

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38 minutes ago, icester said:

Your questions are answered and just need to read the history more carefully...

I think everyone can see that you have failed to answer.

39 minutes ago, icester said:

And since you are not answering my questions

You are the one making new claims, so you are the one that needs to answer questions.

Another one: what is the evidence for your new magic force that no one else has ever seen?

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2 minutes ago, icester said:

OK, please provide an example of correct setup...

You've been given several pictures already. Do you really need an identical one? I don't see how that will help.

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Just now, swansont said:

You've been given several pictures already. Do you really need an identical one? I don't see how that will help.

Just for convenience please point me to at least one such example setup....

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7 minutes ago, icester said:

Just for convenience please point me to at least one such example setup....

An alternative would be dropping a magnet through a coil of wire

Here are my results when I did that (1200 turns of wire, coil was half a meter or so tall)

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Just now, swansont said:

An alternative would be dropping a magnet through a coil of wire

Here are my results when I did that (1200 turns of wire, coil was half a meter or so tall)

I fail to see connection between those assumptions and experimental setup that existed in reality...

First link just shows scope traces and talks about induction which is related to changing field not constant uniform one and the second link is just a calculator not an existing experimental setup...

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1 hour ago, icester said:

I fail to see connection between those assumptions and experimental setup that existed in reality...

You think people just make this stuff up?

Why don't you do an experiment with a wire moving through a magnetic field and test it yourself?

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3 hours ago, icester said:

I fail to see connection between those assumptions and experimental setup that existed in reality...

That’s the point. Your setup IS NOT THE SAME as the one in these descriptions. That’s why your experiment failed. You did it wrong.

Quote

First link just shows scope traces and talks about induction which is related to changing field not constant uniform one and the second link is just a calculator not an existing experimental setup...

It was a link you provided, and you need a changing field flux to get an EMF. Your spinning magnet has a constant field, as configured, which is why you get no result.

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2 minutes ago, swansont said:

That’s the point. Your setup IS NOT THE SAME as the one in these descriptions. That’s why your experiment failed. You did it wrong.

It was a link you provided, and you need a changing field to get an EMF. Your spinning magnet has a constant field, as configured, which is why you get no result.

Those descriptions are unrelated to Lorentz formula F=q*v*B or I*B*L...

The calculator description states " The voltage generated in a length of wire, presuming that the entire length moves through a uniform field, is given below. "

If it required changing field the parameters describing the change would be in input fields... But there is no single experimental setup that confirms the EMF...

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13 minutes ago, icester said:

Those descriptions are unrelated to Lorentz formula F=q*v*B or I*B*L...

Your experiment has no free charges, or current. So what’s your point?

Quote

The calculator description states " The voltage generated in a length of wire, presuming that the entire length moves through a uniform field, is given below. "

If it required changing field the parameters describing the change would be in input fields... But there is no single experimental setup that confirms the EMF...

The equation given is V = vBL

The rate of change of the flux depends on those variables.(I mistakenly wrote field earlier, rather than flux)

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43 minutes ago, icester said:

Those descriptions are unrelated to Lorentz formula F=q*v*B or I*B*L...

Why do you keep talking about force, when you are measuring voltage?

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1 minute ago, Strange said:

Why do you keep talking about force, when you are measuring voltage?

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11 minutes ago, icester said:

Good grief.

I think you should ask for this thread to be closed before you embarrass yourself further.

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1 minute ago, Strange said:

Good grief.

I think you should ask for this thread to be closed before you embarrass yourself further.

Well if you find it distasteful you do not have to post...

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28 minutes ago, icester said:

Did you read the link? It explains that EMF is a voltage, not a Newtonian force.

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It also explains that the relevant equation is Faraday's Law, not Lorentz Law.

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7 minutes ago, Strange said:

It also explains that the relevant equation is Faraday's Law, not Lorentz Law.

Read the chapter "10.2 Motional EMF"

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1 hour ago, icester said:

Those descriptions are unrelated to Lorentz formula F=q*v*B or I*B*L..

Not really, no.

These "formulae" are so bad they are not even wrong.

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Just take a magnet and drop it thru a 3 foot copper pipe and see it slow down compared to

dropping it in air.  This means moving magnetic field induces opposite field in the copper pipe.

Thus moving a magnet or a wire in the field creates an EMF wave.

Edited by Doug Jones

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16 minutes ago, Doug Jones said:

Just take a magnet and drop it thru a 3 foot copper pipe and see it slow down compared to

dropping it in air.  This means moving magnetic field induces opposite field in the copper pipe.

Thus moving a magnet or a wire in the field creates an EMF wave.

Yes, but that is eddy current and induction... Take a 3 foot magnet magnetized perpendicular to it's length and drop a copper ring around it and no effect at all because acceleration is two low for the force to make visible effect...

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1 hour ago, icester said:

Yes, but that is eddy current and induction...

Is that supposed to have any particular meaning? ALL of this is induction.

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9 hours ago, swansont said:

Is that supposed to have any particular meaning? ALL of this is induction.

No, static magnetic field does not induce EMF:  https://en.wikipedia.org/wiki/Induction_equation