What's wrong with this diagram of magnetic field lines?

[magnetics]

I was looking through a book on magnetism and it had the attached diagrams of field lines and stated that the classical diagram of field lines exiting the N pole and entering the S pole is incorrect. They claim their diagram is the correct representation of the magnetic field lines.

Their rationale is that if you take a long bar magnet, there is a strong magnetic attraction at the ends but very little in the middle.

But isn't this observation due to field gradients? That is, the field lines curve at the ends of a bar magnet and the field is strongly inhomogeneous, while at the middle of the bar magnet the field lines are almost parallel and the field is almost homogeneous.

Thank you.

 

[sophiecentaur]

The book is wrong. Read three others and take a majority decision!

 

[magnetics]

Well thanks for that sophiecentaur.
I know the book is wrong, what I was hoping for is a clear explanation as to why it's wrong :)

 

[ZapperZ]

What am I missing here?

I looked at the attachment, and it had the phrase "Mistaken Concepts of Magnetism" in the title of the figure. If you took this from the book, what is wrong here? The picture IS showing the mistaken concepts of the magnetic field of the Earth and a bar magnet. So the book is correct that these are mistakes!

Zz.

 

[sophiecentaur]

It's wrong because the fields are not like that. It's a bit of a waste of time trying to find what's wrong about something unless you are trying to put someone right. Neither of us can tell the author how he's wrong so just ignore it. Presumably you can get a 'clear explanation' of the right description (any decent textbook). Maxwell's Equations do not describe it like that - see what they, correctly, predict. (http://www.sfu.ca/physics/associate/emeriti/cochran/MAX.pdf). If, like me, you would rather not go in that deep, just take it as correct.
The flaw is in how he's drawn the lines between the two intermediate poles. Why don't the lines go from the inner N to the inner S? If they do what the diagram says at that point, why don't they do it along the whole length of the magnet - wherever you choose to introduce a gap?

 

[ZapperZ]

But the author IS trying to show that the fields are not like that! Isn't that what "Mistaken Concepts of Magnetism" accompanying the figure would imply?

Zz.

 

[sophiecentaur]

But the author IS trying to show that the fields are not like that! Isn't that what "Mistaken Concepts of Magnetism" accompanying the figure would imply?

Zz.

You are absolutely right. But diagrams like that in books should always have a bold cross over them to avoid anyone taking them seriously. Let's face it, he may just as well have drawn a picture with pink elephants pulling at the lines with their trunks.

 

[ZapperZ]

You are absolutely right. But diagrams like that in books should always have a bold cross over them to avoid anyone taking them seriously. Let's face it, he may just as well have drawn a picture with pink elephants pulling at the lines with their trunks.

But that's missing the point here, isn't it? We're talking about whether the book is correct or not. The issue of whether it is clear or not is a different matter. And obviously, to me, it was VERY clear since I saw the title of the figure right off the bat.

It makes this whole thread rather moot, because there's nothing wrong with this book. The magnetic field lines ARE wrong, and the author of the book clearly stated that these are wrong as well. In other words, the book hasn't stated something wrong.

What is wrong is the starting premise of this thread.

Zz.

 

[magnetics]

Sorry, maybe I should have totally ridiculed the authors from the start so as to not give the wrong impression, but I try to always see things from the other person's perspective.

On the previous page of the book they show the Earth's and a bar magnet's field lines in the classical way which they then describe as incorrect - this is what they say is mistaken. The picture I attached is the authors idea of a correction and I explained their rationale as described in the book.

Admittedly the book was first published in 1974, but where did they go wrong?

 

[Crazymechanic]

what do yu mean they show the classical way and then go on to say that's incorrect , are you saying that the authors first make a picture of how things should be and say it's wrong and then show how things shouldn't be and call that also wrong , then what is right ?

I think it would be great if you could show the previous page you were talking about , there have been many physics books over the years .

Why would the authors show a picture of field lines they think should be correct and then go on to put a title that goes like " Mistaken concepts" ? Sounds very strange.

 

[Drakkith]

Where did they go wrong? At the very beginning. You can easily see the field lines of a bar magnet by using iron filings.

 

[magnetics]

Another question could be, why is there very little magnetic attraction in the middle of a bar magnet? This is what I was trying to draw out.

 

[ZapperZ]

Sorry, maybe I should have totally ridiculed the authors from the start so as to not give the wrong impression, but I try to always see things from the other person's perspective.

On the previous page of the book they show the Earth's and a bar magnet's field lines in the classical way which they then describe as incorrect - this is what they say is mistaken. The picture I attached is the authors idea of a correction and I explained their rationale as described in the book.

Admittedly the book was first published in 1974, but where did they go wrong?

Sorry, but you're making very little sense here.

After read what you've written, I'm leaning towards giving the benefit of a doubt in the book's favor.

Zz.

 

[Crazymechanic]

Maybe just write down here the title of the book and the authors and publishing year.And I'm sure Zapper or others will tell either the book is wrong or your take on the book is wrong.

the weakest part of the field so to say is in the middle because fields of same strength but opposite poles comes together the same distance and cancel out , break the magnet in half and you get two new magnets each with a N and a S.and now the middle point is again between those two.

 

[magnetics]

what do yu mean they show the classical way and then go on to say that's incorrect , are you saying that the authors first make a picture of how things should be and say it's wrong and then show how things shouldn't be and call that also wrong , then what is right ?

I think it would be great if you could show the previous page you were talking about , there have been many physics books over the years.

Here it is in black and white, see attached.
Yes, they go on and describe what subscribers to the Physics Forums would call the impossible and the implausible!

 

[Drakkith]

Here it is in black and white, see attached.
Yes, they go on and describe what subscribers to the Physics Forums would call the impossible and the implausible!

What book is this?

 

[Crazymechanic]

ok give us the name of the book and the authors, so you say that the first picture you attached in the Original Post is the one that the authors say is the right one?

 

[ZapperZ]

Here it is in black and white, see attached.
Yes, they go on and describe what subscribers to the Physics Forums would call the impossible and the implausible!

They simply can't get any more obvious than highlighting it in the TITLE of the chapter!

I still do not see what is wrong with this book. What you had described and shown so far seemed to reveal more of your misunderstanding of the authors were trying to do and show.

Zz.

 

[sophiecentaur]

I think the clue is in the typeface used. It says 'pulp'.

 

[magnetics]

It's called "Magnetism and its effects on the living system". By Davis & Rawls. First published in 1974 by Acres USA.

It's not a textbook on physics and I think the disbelief that someone could have even published such nonsense has hijacked the original premise of my question.

 

[ZapperZ]

It's called "Magnetism and its effects on the living system". By Davis & Rawls. First published in 1974 by Acres USA.

It's not a textbook on physics and I think the disbelief that someone could have even published such nonsense has hijacked the original premise of my question.

Er... no. I've seen enough crackpottery being published in books that I do not put it past any author or publisher to have no shame to reveal their ignorance.

The problem here is that I STILL do not see, from all your attachements, on where this book has made a mistake! The FIRST figure you showed, what exactly is wrong in that attachment? We ALL know the field lines are wrong, and the attachment even MENTIONED that it is wrong! This is why I was scratching my head in trying to figure out the problem you're having with it!

The second attachment reinforced my original view, because the authors are now starting it very clearly in the TITLE OF THE CHAPTER! So of course, one would expect that, in that chapter, you'll see a LOT of wrong stuff!

<scratching head>

Zz.

 

[Crazymechanic]

As far as I can tell by looking it up the book is simply wrong.
so the examples you posted in your OP are the ones that the authors say are the right ones or aka their way of explaining things aren't they? Atleast I get the same picture sin google with their words on them said it's their theory. ?

I think the misunderstanding is here because the title is the title of the whole paragraph in which the authors try to explain their view or take on tings , first showing the traditional accepted way and then goign on with their own way, keeping the title the same in each page , am I correct @magnetics?

Look it up Zapper :)

 

[sophiecentaur]

It's wrong because the fields are not like that. It's a bit of a waste of time trying to find what's wrong about something unless you are trying to put someone right. Neither of us can tell the author how he's wrong so just ignore it. Presumably you can get a 'clear explanation' of the right description (any decent textbook). Maxwell's Equations do not describe it like that - see what they, correctly, predict. (http://www.sfu.ca/physics/associate/emeriti/cochran/MAX.pdf). If, like me, you would rather not go in that deep, just take it as correct.
The flaw is in how he's drawn the lines between the two intermediate poles. Why don't the lines go from the inner N to the inner S? If they do what the diagram says at that point, why don't they do it along the whole length of the magnet - wherever you choose to introduce a gap?

Er... no. I've seen enough crackpottery being published in books that I do not put it past any author or publisher to have no shame to reveal their ignorance.

The problem here is that I STILL do not see, from all your attachements, on where this book has made a mistake! The FIRST figure you showed, what exactly is wrong in that attachment? We ALL know the field lines are wrong, and the attachment even MENTIONED that it is wrong! This is why I was scratching my head in trying to figure out the problem you're having with it!

The second attachment reinforced my original view, because the authors are now starting it very clearly in the TITLE OF THE CHAPTER! So of course, one would expect that, in that chapter, you'll see a LOT of wrong stuff!

<scratching head>

Zz.

My earlier post includes a good reason why it's wrong.

 

[Crazymechanic]

this is one of those free energy, magnet walls, Bloch wall in the middle of a magnet type of things , it's not wrong it's just absurd

@magnetics you are right , the authors are wrong.

It's just that the whole paragraph is called in one name that made some members confused here.

 

[ZapperZ]

My earlier post includes a good reason why it's wrong.

What is "it" here? "it" as in the magnetic field lines, or "it" as in the attachment? All I saw were your argument on why the fields are wrong. Please be clear on this: no one is disputing that!.

What I'm disputing is the claim that the whole attachment is wrong, and that is false! The TITLE of first attachment CLEARLY indicates that these are the misconception of magnetic fields! Your argument that the fields are wrong simply supported what the book was trying to present?

I am puzzled why this is so confusing to understand!

Zz.

 

[magnetics]

The problem here is that I STILL do not see, from all your attachements, on where this book has made a mistake! The FIRST figure you showed, what exactly is wrong in that attachment? We ALL know the field lines are wrong, and the attachment even MENTIONED that it is wrong! This is why I was scratching my head in trying to figure out the problem you're having with it!

<scratching head>

Zz.

The attachment had the tile "Mistaken Concepts of Magnetism". This is the name of the chapter.

 

[magnetics]

I think the misunderstanding is here because the title is the title of the whole paragraph in which the authors try to explain their view or take on tings , first showing the traditional accepted way and then goign on with their own way, keeping the title the same in each page , am I correct @magnetics?

Crazymechanic has nailed it!

 

[ZapperZ]

The attachment had the tile "Mistaken Concepts of Magnetism". This is the name of the chapter.

Yeah, so? The figure they showed has the wrong magnetic fields, and this is consistent with the intention of the chapter, no? So what's wrong here?

Look, I'm going to say "A is wrong. Let me show you"

And then you complain that I showed you something wrong.

I then say "But wait, that's my intention! I TOLD you that I'm going to show you A!"

But you continue to complain "Yeah, but A is wrong! It can't be like that!"

I walk away and shake my head.

Zz.

 

[sophiecentaur]

All this is the result of a set of a multiple negatives, I think.
But I would really like to have that second attachment explained. That seems to be saying that the 'right' theory is 'wrong'. Is it from the same book? Or is the original book just quoting another book that happens to be wrong about what's wrong?

 

[Crazymechanic]

Ok I understand Zappers confusion as he thinks the title has anything to do with what the authors actually say but this is not the case , look up the book Zapper , it's rubbish.

Magnetics please be so kind and post the full page layout of the authors proposed design where they say that A model is wrong and b model is right , B model being that model in the OP first attached picture which is clearly wrong.Guys chill down and let the OP post the full pages of the book that I mentioned and you will see for yourselves , I have a youtube video I could show about the book but it's crackpot video so I don't want to show it now let the OP show himself if we will not make any success then I will let you see the vidoe about the book.