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Author Topic: Magnet Myths and Misconceptions  (Read 605800 times)

Newton II

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Re: Magnet Myths and Misconceptions
« Reply #45 on: October 03, 2014, 03:34:26 PM »
You can define a magnetic field as a cloud of tiny purple honeybees swarming in tune to a Sosa march if you like.


I don't think honeybees are swarming!

Another interesting (crazy) observation :

It doesnot look like moving electrons produce magnetic field.  If moving electron produces magnetic field, then magnetic field should also move with the electron producing it.   Hence we should feel the force or vibration of moving magnetic field externally near a coil.

But practically we observe that when a direct current is passed through a coil, we get a static magnetic field at the centre of  coil and we don't feel any force (or vibration)  of a moving magnetic field.

Does it mean that when electron starts moving, mother nature provides it with an armour in the form of magnetic field to protect it from attacking enemies??!!!  Is magnetic field  produced by moving electron or nature? (vaccuum)

Can anybody explain why a moving electron current in a coil produces a static magnetic field at the centre?

 

MileHigh

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Re: Magnet Myths and Misconceptions
« Reply #46 on: October 03, 2014, 09:37:18 PM »
What do you mean when you say "feel a force or vibration?"

TinselKoala

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Re: Magnet Myths and Misconceptions
« Reply #47 on: October 04, 2014, 01:07:46 AM »
What do you mean when you say "feel a force or vibration?"

What happens when you poke a straw man with a knitting needle?

Newton II

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Re: Magnet Myths and Misconceptions
« Reply #48 on: October 04, 2014, 03:44:06 AM »
What do you mean when you say "feel a force or vibration?"

I have said 'force or vibration of a moving magnetic field'. 


If you pass an AC through a coil and take a iron piece near the coil, iron piece vibrates indicating that the magnetic field produced by coil is in some sort motion or oscillation.

But if you pass a DC through the coil and bring a iron piece near it, you won't feel any vibration of the iron piece and it simply gets attracted to the coil indicating that magnetic field is stagnant.

My question is why moving electrons in a DC produce static magnetic field in the coil? 

What happens if you hammer a crowbar ( mega needle ) into strawman's ass ?? :-\



MileHigh

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Re: Magnet Myths and Misconceptions
« Reply #49 on: October 04, 2014, 05:58:16 AM »
A continuous flow of unchanging DC current will produce a continuous unchanging magnetic field.  Easily confirmed by experimental observation.

You want to get more technical?  Study this guy's clips:

https://www.youtube.com/watch?v=4c6fRmyh4q8&list=UU6x7DywfEqLg-3Cg_JnyTlg

Newton II

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Re: Magnet Myths and Misconceptions
« Reply #50 on: October 04, 2014, 10:50:21 AM »
A continuous flow of unchanging DC current will produce a continuous unchanging magnetic field.  Easily confirmed by experimental observation.


I know that a uniform DC produces unchanging magnetic field at the centre. 

Whether this unchanging flux remains static or rotates around a vertical axis following the path of moving electrons? When a moving electron produces magnetic field, the magnetic field should also move along with it, is it not?

Will the  magnetic field produced by a permanent magnet remains static or will it rotate around a vertical axis following the path of electrons producing that magnetic field?

If you don't understand my question- leave it - no problem.

The existance of magnetic field, transformation of electric field to magnetic field and other strange properties of magnetic field are beyond the scope of ordinary cracknuts. Better forget about all those things and enjoy playing with 'magnetic black holes'.


https://www.physicsforums.com/threads/why-does-moving-electron-produce-magnetic-field.184619/

http://en.wikipedia.org/wiki/Quantum_vortex


Marsing

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Re: Magnet Myths and Misconceptions
« Reply #51 on: October 04, 2014, 12:13:40 PM »

someone said in TA thread that magnetic field is move at ~60x speed of light, magnetic field is not static but i dont know he said that for PM or electromagnet (coil) or both. i can not recall his name. 

poynt99

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Re: Magnet Myths and Misconceptions
« Reply #52 on: October 04, 2014, 03:13:34 PM »
I have said 'force or vibration of a moving magnetic field'. 


If you pass an AC through a coil and take a iron piece near the coil, iron piece vibrates indicating that the magnetic field produced by coil is in some sort motion or oscillation.

But if you pass a DC through the coil and bring a iron piece near it, you won't feel any vibration of the iron piece and it simply gets attracted to the coil indicating that magnetic field is stagnant.
There really is no difference between these two scenarios.

Quote
My question is why moving electrons in a DC produce static magnetic field in the coil? 
This is the pertinent question.

But I don't think the question is "why" as much as it is "how". I believe the magnetic field is produced because the electron field around the individual atoms become aligned with each other.

But how does applying a DC voltage/voltage cause this alignment? There does not seem to be a maximum alignment like there is with aligning domains in a core material.

mondrasek

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Re: Magnet Myths and Misconceptions
« Reply #53 on: October 04, 2014, 05:39:17 PM »
But I don't think the question is "why" as much as it is "how". I believe the magnetic field is produced because the electron field around the individual atoms become aligned with each other.

But how does applying a DC voltage/voltage cause this alignment? There does not seem to be a maximum alignment like there is with aligning domains in a core material.

I had not considered this before.  The relationship between current "flow" and the corresponding magnetic field "strength" increases as 1:1 (heating losses aside) as far as testing has shown?  There is no apparent, or theoretical limit?

MileHigh

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Re: Magnet Myths and Misconceptions
« Reply #54 on: October 04, 2014, 06:09:59 PM »
Newton II:

I could not fine the right clip to link to yesterday, but I found it today:

"Calculating the Magnetic Field due to a Moving Point Charge"

https://www.youtube.com/watch?v=waTF7kjmmt8&list=UU6x7DywfEqLg-3Cg_JnyTlg&index=47

So for a moving point charge you can say that it is any value of charge, even the charge associated with a single electron.  If you watch the clip you will see that there is a magnetic field that envelopes the single moving electron and it moves along with the electron.

Magnetic fields are vectors with magnitude and direction.  If you have multiple magnetic field vectors at a single point in 3D space due to multiple moving electrons in a wire, then they all add together.

So, you do have a moving magnetic field for each moving electron.  So each distinct point in 3D space around the wire is affected by trillions and trillions of magnetic field vectors due to trillions and trillions of moving individual electrons.  The net result of all of these trillions and trillions of magnetic field vector additions when you have DC current is that you have a single unchanging magnetic field vector at a given point in 3D space.

It's as simple (or complicated) as that.

One of the myths is that when you hold two magnets with opposing poles next to each other and you feel the repulsion between the poles that you have "stressed space" in the region between the two opposite poles.  That's just a myth.  A person feels the repulsion and says, "that must be special stressed space."  The magnetic field vectors from each magnet are simply passing through the same 3D space and crossing paths without even being "aware" that the other magnet is there.  The magnetic field vectors are just "blindly" adding together to create a new net magnetic field with a new magnitude and direction at every point in 3D space.

Another myth is that people believe that something must be "circulating around" because they look at diagrams with magnetic field lines of force represented as circles with directional arrows.  It's just a myth self-created from looking at diagrams on paper.

You can just as easily feel forces between two charged objects due to an electric field between the two objects but that is a much rarer occurrence for experimenters so they don't even think about it.

You can "stress" space with electric fields and magnetic fields.  What actually is an electric field?  What actually is a magnetic field?   I don't know but it almost like going up to taste tester for a five star restaurant and asking him to describe the taste of water.

MileHigh

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Re: Magnet Myths and Misconceptions
« Reply #55 on: October 04, 2014, 06:10:12 PM »
Here is what people forget all the time:  The magnetic field doesn't just "magically appear" when you have current flowing.  It tales electrical WORK (voltage x current x time) to get the current flowing and create the magnetic field.  Where does that work go?  The answer is the work goes into the actual 3D space around the wire.  A certain value of magnetic field intensity in a one-centimeter cube of 3D space next to a wire with current flowing through it has a certain amount of stored energy associated with it.  There is literally energy stored in empty 3D space because of the existence of the magnetic field.  The same thing applies to electric fields.

Here is an analogy that I think is quite useful:   Think of a long straight wire.  Think of a long straight balloon.  Now put the wire inside the balloon.  Forget about the ends of the balloon and all that stuff.  It's a "magic" balloon with no ends.

Now, when there there is no current flowing through the wire the balloon is deflated.   When current flows through the wire, at the beginning you have to do some extra work to inflate the balloon.  Once the balloon is inflated to a certain diameter then there is no extra work required to keep the current flowing.   Can you picture that?   The inflated balloon is not changing in diameter either, so there is no extra work required to keep the balloon inflated.

The membrane of the balloon is under tension - it's stressed.  The inflated balloon represents a certain amount of stored energy per unit length of wire.

That "stressed balloon" is analogous to the stressed 3D space around the wire due to the presence of the magnetic field.

It's just stressed 3D space, there is nothing "flowing" there are not necessarily any "flowing particles" that some people what to believe exist.  I am no expert into the sub-atomic quantum realm and perhaps there is research going on there.  What I can say is that we CAN MEASURE the magnetic field and we UNDERSTAND that this represents stressed 3D space that stores energy, just like the inflated balloon stores energy.

Then when you shut off the current flow through the wire by opening a switch, the balloon deflates and gives back the energy that was originally expended to create it in the first place.  There is your high-voltage spike.  To be more precise, it is a small amount of continuing current flow that also manifests itself as a high-voltage spike.

One of the important lessons here is to "never take your eye off of the 'energy ball'"   A magnetic field in 3D space represents the storage of energy per unit volume of space.  Electrical energy was used to create that energy storage in 3D space and electrical energy is given back, or output, when the magnetic field collapses.

MileHigh

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Re: Magnet Myths and Misconceptions
« Reply #56 on: October 04, 2014, 06:43:47 PM »
Here is another story to ponder....

Yes, when you measure a static magnetic field around a wire with DC current flowing through it, it's actually the vector summation of trillions and trillions of moving magnetic field "sheaths" that surround the moving electrons in the wire.

Now, when you go to inflate your tire and you measure the tire pressure with a pressure gage, you measure 30 pounds per square inch.   In reality, that pressure is created by trillions and trillions (?) of oxygen and nitrogen and other molecules hitting the pressure transducer plate per second inside tire pressure gage.

So how often when you fill up your tires in a gas station do you say to yourself, "It's not really PSI, it's actually trillions of air molecules bouncing around and hitting the pressure transducer plate inside the tire pressure gage.?"

The answer is that you almost never say that to yourself.  Just like when you do experiments on the bench and you measure the magnetic field around an inductor or a bar magnet you don't have to always be thinking about the trillions and trillions of moving electrons.

These crazy myths and misconceptions about magnets and magnetism will live on forever.  But at least if you are a serious researcher and experimenter around here you should undertake to learn these things and accept them for the physical and verifiable reality that they represent so that you can do better and smarter experiments.  To say, "By default I want to believe in 'alternative' explanations because they are 'cooler'" is honestly just plain stupid.  This compulsion to "go against the grain" because you have a belief that you are supposed to go against the grain is ultimately counterproductive.  Do the research and experiments and figure things out for yourself.

One classic example of this is the stupid "series bifilar" coil.  You see people do experimental setups where by default they wind their coil in a series bifilar configuration.  In 99% of the cases it's nonsensical electronics quackery in action.  Whether you just make an ordinary coil or make a "series bifilar" coil makes no difference.  The only thing that counts is the number of turns.

People don't even know why they are winding a series bifilar coil.  I have to assume that the main reason they do it is because everybody else is doing it.  That is a HUGE mistake and shows people not wanting to actually understand.  That is a problem if you are supposed to be doing research.  This kind of incorrect way of thinking can be traced back as one of the root causes of the Quantum Energy Generator quackery and the loss of hundreds of thousands of dollars given to con artists.

Qwert

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Re: Magnet Myths and Misconceptions
« Reply #57 on: October 04, 2014, 08:18:26 PM »
a moving electron produces magnetic field, the magnetic field should also move along with it, is it not?
Fundamental misunderstanding: electron does not move this way!! The best explanation is here, and believe it or not, this is the best explanation IMHO:

Electrons in metals do not hold still.  They wiggle around constantly even when there is zero electric current.  However, this movement is not really a flow, it is more like a vibration, or like a high-speed wandering movement...
see the whole article here:
 http://amasci.com/miscon/speed.html
and more K-6 revelations... where K stands for kindergarten

lumen

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Re: Magnet Myths and Misconceptions
« Reply #58 on: October 04, 2014, 08:38:54 PM »
What happens when you poke a straw man with a knitting needle?

He says hay?

Newton II

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Re: Magnet Myths and Misconceptions
« Reply #59 on: October 04, 2014, 09:16:58 PM »

@Milehigh

You have done a smart research work. Hats off for that.

1) Now we agree that a moving electron produces magnetic field which moves along with electron.   

2) The magnetic fields  produced by infinite number of electrons add together resulting in a external strong magnetic field which seems   
     to be static but theoritically will have a vectorial movement.

3) When moving electrons are stopped, the stored energy in electrons is dissipated as a EM wave.

This may lead to another thinking that is magnetic field produced by an electron analogous to the kinetic energy developed by a solid moving mass?

In mechanics a solid mass 'm'  moving with velocity 'v' develops  kinetic energy  of  ½ mv2.   But when you supply energy to the electrons by applying voltage, the electron  cannot store energy in the form of   ½ mv2  because its mass is negligible.  So it creates a magnetic field to store the supplied energy.   When electrons are stopped, energy is released as EM wave.

So, if you study the magnetic field carefully you will know what is energy.

Does it make any sense or just a blah-blah?