swansont Posted March 5, 2018 Posted March 5, 2018 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.
Butch Posted March 5, 2018 Author Posted March 5, 2018 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)?
swansont Posted March 5, 2018 Posted March 5, 2018 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.
Butch Posted March 5, 2018 Author Posted March 5, 2018 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?
swansont Posted March 5, 2018 Posted March 5, 2018 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.
michel123456 Posted March 5, 2018 Posted March 5, 2018 41 minutes ago, swansont said: 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. But motion is relative.
Strange Posted March 5, 2018 Posted March 5, 2018 1 minute ago, michel123456 said: But motion is relative. Which means that some people may see a magnetic field and others not.
swansont Posted March 5, 2018 Posted March 5, 2018 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.
Butch Posted March 5, 2018 Author Posted March 5, 2018 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). 1
michel123456 Posted March 7, 2018 Posted March 7, 2018 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?
Strange Posted March 7, 2018 Posted March 7, 2018 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.
Butch Posted March 7, 2018 Author Posted March 7, 2018 1 minute ago, Strange said: Only if the human is electrically charged. Can we say that charge is just the origin of a field.
Strange Posted March 7, 2018 Posted March 7, 2018 31 minutes ago, Butch said: Can we say that charge is just the origin of a field. 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.
swansont Posted March 7, 2018 Posted March 7, 2018 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.
Butch Posted March 7, 2018 Author Posted March 7, 2018 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!
Strange Posted March 7, 2018 Posted March 7, 2018 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.
Butch Posted March 7, 2018 Author Posted March 7, 2018 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!
swansont Posted March 7, 2018 Posted March 7, 2018 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.
Butch Posted March 7, 2018 Author Posted March 7, 2018 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?
swansont Posted March 8, 2018 Posted March 8, 2018 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.
Butch Posted March 9, 2018 Author Posted March 9, 2018 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?
Strange Posted March 9, 2018 Posted March 9, 2018 6 minutes ago, Butch said: Am I right to say that enter and exit are arbitrary, since time is irrelevant? The field lines are vectors, so entry and exit are not irrelevant.
Butch Posted March 9, 2018 Author Posted March 9, 2018 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.
Strange Posted March 9, 2018 Posted March 9, 2018 (edited) 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 March 9, 2018 by Strange
Butch Posted March 9, 2018 Author Posted March 9, 2018 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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