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"Intrinsic angular momentum"


Butch

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23 minutes ago, Butch said:

Of course, silly me! However why classically a moving charge, isn't that relative?

A stationary charge just has an electric field. A moving charge has a magnetic field, because that's what happens to an electric field when you transform it into a moving frame.

With circular motion you get a magnetic moment you can associate with it.

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1 minute ago, swansont said:

A stationary charge just has an electric field. A moving charge has a magnetic field, because that's what happens to an electric field when you transform it into a moving frame.

With circular motion you get a magnetic moment you can associate with it.

So, same field just a matter of affectation (Relative) or self reference(circular motion)?

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Just now, Butch said:

So, same field just a matter of affectation (Relative) or self reference(circular motion)?

It's not the same field, per se, since they behave differently, and the electric field doesn't disappear.

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12 minutes ago, swansont said:

It's not the same field, per se, since they behave differently, and the electric field doesn't disappear.

By disappear you mean lack of relative motion? 

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58 minutes ago, Butch said:

By disappear you mean lack of relative motion? 

I mean that a charged particle will have an electric field, regardless of its motion. When it moves it has a magnetic field in addition to an electric field.

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40 minutes ago, michel123456 said:

But motion is relative. 

Yes. When you are in the rest frame of the charge there is no magnetic field. When you are in relative motion, there is a magnetic field.

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4 hours ago, swansont said:

Yes. When you are in the rest frame of the charge there is no magnetic field. When you are in relative motion, there is a magnetic field.

Thx, my ego just grew by an angstrom!(relatively speaking).

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On 3/5/2018 at 7:22 PM, swansont said:

Yes. When you are in the rest frame of the charge there is no magnetic field. When you are in relative motion, there is a magnetic field.

Then, who is the "producer" of the magnetic field?

From the charge frame, there is no magnetic field produced by it. The same for us: from our frame we are not producing any magnetic field. We have an equal POV.

It may be that when the charge observes a human moving, a magnetic field appears and the charge says: hey, the human is producing a magnetic field. Or am I wrong somewhere?

 

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7 minutes ago, michel123456 said:

It may be that when the charge observes a human moving, a magnetic field appears and the charge says: hey, the human is producing a magnetic field. Or am I wrong somewhere?

Only if the human is electrically charged.

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3 hours ago, michel123456 said:

Then, who is the "producer" of the magnetic field?

From the charge frame, there is no magnetic field produced by it. The same for us: from our frame we are not producing any magnetic field. We have an equal POV.

But you don't have an identical POV.

The fields produced by a charge depends on the frame of reference. Much like time and length depend on your frame.

3 hours ago, michel123456 said:

It may be that when the charge observes a human moving, a magnetic field appears and the charge says: hey, the human is producing a magnetic field. Or am I wrong somewhere?

You are wrong.

2 hours ago, Butch said:

Can we say that charge is just the origin of a field.

Origin or termination. The divergence of the field depends on the charge.

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3 hours ago, swansont said:

Origin or termination. The divergence of the field depends on the charge.

Are you saying polarity?

6 hours ago, Strange said:

That is not unreasonable: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elefie.html

Although you could say the field is always there but is zero in the absence of charge.

Excellent link, however the innies and outies are not real, just assumed for our reference. I really need to be discussing this in my micro/macro topic in speculations.

Aha! You have pushed me to discovery! See you in speculations!

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24 minutes ago, Butch said:

Excellent link, however the innies and outies are not real, just assumed for our reference.

I’m not sure what you mean by “real” but the field is not scalar; ie it has direction. 

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1 minute ago, Strange said:

I’m not sure what you mean by “real” but the field is not scalar; ie it has direction. 

I mean we could use negative charge as our reference and a field would be measured via it's influence on a negative charge... You are the terminology Guru, I should have said arbitrary. Thx again, excellent link... tfgtfm!

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45 minutes ago, Butch said:

Are you saying polarity?

No.

The field lines entering or leaving a volume depends on the enclosed charge. They start or end on charges. If there's no charge enclosed, the field lines have to enter and leave.

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12 minutes ago, swansont said:

No.

The field lines entering or leaving a volume depends on the enclosed charge. They start or end on charges. If there's no charge enclosed, the field lines have to enter and leave.

Sorry, that is not soaking in...

If a point in space has a positive charge and no other charge is in play the flux density at any given point would be determined by the inverse square... 

What is meant by start and end?

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17 hours ago, Butch said:

Sorry, that is not soaking in...

If a point in space has a positive charge and no other charge is in play the flux density at any given point would be determined by the inverse square... 

What is meant by start and end?

The field lines emanate from that charge. If it were negative, they would terminate on the charge (the field is a vector) 

If you draw a volume around it, there are field lines leaving the volume, through the surface. If there is no charge in the volume, then any line that enters also leaves the volume.

This is introductory electrostatics.

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On 3/8/2018 at 11:59 AM, swansont said:

The field lines emanate from that charge. If it were negative, they would terminate on the charge (the field is a vector) 

If you draw a volume around it, there are field lines leaving the volume, through the surface. If there is no charge in the volume, then any line that enters also leaves the volume.

This is introductory electrostatics.

Thank you for the introduction... I get it!

Am I right to say that enter and exit are arbitrary, since time is irrelevant?

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27 minutes ago, Strange said:

The field lines are vectors, so entry and exit are not irrelevant.

Never said irrelevant, -1 + 1 = 0 if we flip things so that positive is the left side the math holds true.

When we say entering or exiting we are actually just stating a polarity relationship, correct?... I am sorry if I seem to be beating on an unimportant point, I just want to be sure it is unimportant.

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2 minutes ago, Butch said:

Never said irrelevant, -1 + 1 = 0 if we flip things so that positive is the left side the math holds true.

Sorry, I misread it. Well the convention about positive and negative charge is arbitrary. But the convention is now fixed. You can only change the direction of the field lines if you also flip the charge.

Edited by Strange
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2 minutes ago, Strange said:

Sorry, I misread it. Well the convention about positive and negative charge is arbitrary. But the convention is now fixed. You can only change the direction of the field lines if you also flip the charge.

Thx

Ok, thanks all... I get it... I think I am ready to dive into quarks, any suggested links?

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