Mad Teddy's web-pages

Electromagnetism - some thoughts

As mentioned in my Mathematical stuff page, I struggled with physics at school and university, even though I really did want to understand as much as I could about how the universe worked; I also mentioned that it was only after finishing my B.Sc. degree that the pieces began to form an organized picture in my mind.

In early 2005, when I began to build this website, I had in mind to include some pages giving brief descriptions of the various electrical gadgets that I'd made - some (the early ones) with a great deal of input from my Dad - as a lead-in to my rekindled interest in high-voltage things like Tesla coils and electrostatic machines (Wimshurst, Van de Graaff etc.). The pages were to be practical, and light on theory.

However, having started, I developed a growing realization of how many holes there still were in my knowledge of electromagnetism.

Of course, I understood basically how a coil of wire develops a magnetic field when a current flows through it; how an AC current in a transformer's primary induces a corresponding current in its secondary; how a simple commutator-type electric motor works; and how a magnet moving in a coil of wire generates a current in the coil.

Or at least, I thought I did.

Truth is, I never really understood the magnetic stuff. Most kids play with magnets at some stage, and have a simple appreciation of how they have a north pole and a south pole, and how unlike poles attract and like poles repel; and I was no exception. I knew that it had something to do with the way electrons are arranged in the outer "electron shells" of the atoms of certain metals (iron, cobalt and nickel, basically). The simple explanations, without too much detail. "How hard can it be?", I thought.

But then I'd always found textbook treatments of the subject strangely confusing. After the usual introductions involving "lines of force", iron filings, solenoids and so on, they would suddenly become very complicated and technical. I was always left with the feeling that at some point there was a gap in the discussion; that something so inherently simple shouldn't become so difficult, so quickly.

So I dug out some textbooks and buried my head in them, determined to make sense of what they said, comparing their accounts one with the other. I dug around on the internet to find additional material to supplement what the books said. I became a serious student again for a while! And I found some very surprising things.

I found that I wasn't alone in my bewilderment. Lots of websites give the impression that there's a lot more to be said about all this than you'll find in your standard physics textbook.

Also, I remember that, while at university in the 1970's, I'd overheard some second-year engineering students I knew (bright boys, all of them) grumbling about how the subject they had to do called "Electromagnetism" was very difficult. (This was when I was repeating most of first year, and beginning to suspect that I wasn't up to it and would never understand this stuff, and feeling pretty bad about it - which is why I didn't join in the conversation).

So, in my early fifties, I began an assault on the subject. I know I'm not stupid, and I became sufficiently angry with my lack of understanding in the area to do something about it.

These pages are the direct result.

The standard textbook discussion of electromagnetism begins - very properly - with Oersted's discovery of how an electric current in a wire will cause a compass needle to twitch, thus showing that there is some kind of "magnetic field" associated with the current. Then, how Oersted's subsequent experiments led to the conclusion that a cross-section of this "magnetic field" is circular in shape, and has a particular rotational direction (or "sense") depending upon the direction of the current. (Presumably, if you've come from my introductory Electromagnetism page, you'll have seen my take on this.)

The next step, usually, is to talk about what happens if the wire is bent into a loop. Lo and behold, the "magnetic field" now takes on something of the quality of the corresponding phenomenon associated with a permanent magnet: we now have an identifiable north-south effect along the axis of the loop.

Then, the discussion will deal with how a coil made up of many such loops - a solenoid - will exhibit a more obviously linear magnetic effect, and behave very much like a bar magnet. The effect is more pronounced if a rod of iron, or something with similar "magnetic properties" (ferromagnetic), is inserted into the coil. The entire object now becomes an electromagnet, with a definite north pole and a definite south pole. (Again, if you've already visited my introductory Electromagnetism page, you'll know that I've addressed this matter - but, deliberately, from a somewhat different angle.)

Okay - let's stop right there.

Somehow, almost unnoticed, we've progressed from a point where we had a circular magnetic field around a piece of current-carrying wire, with no hint of anything like a north or south pole, to a point where we have an electrical device which looks and behaves for all the world like a bar magnet!

The question is: WHERE DID THE POLES COME FROM?

Now, science is supposed to have nothing to do with magic - right? Yet, as if by magic, we now have two entities coming into existence - apparently - out of thin air!

It won't do. We need to come up with a rational explanation. Here's mine:

The linear nature of the magnetic field has to do with the geometry of the wire. As long as it's straight - as in Oersted's original experiments - there is nothing that can be described as a north pole or a south pole. It's only when we bend the wire that the linear effect, complete with its "poles", becomes apparent.

This is the crucial point. It's here, I believe, that many textbooks at least appear to take a leap into the "wild blue yonder".

Let's consider a permanent magnet for a moment.

If you look at the diagrams in many textbooks, you gain the impression that a bar magnet has "lines of force" which exist in the space around the object. Apparently, these emanate from the poles.

So what happens in the space actually occupied by the magnet? Do the "lines of force" come to an abrupt end at each pole, with the actual material just sitting there like some kind of passive lump, and not contributing to the proceedings in any obviously meaningful way?

You could be forgiven for suspecting this - until you consider what happens if you cut a bar magnet into shorter pieces. Guess what? A new "pole" apparently comes into existence at each cut end of the resulting pieces. (More magic...?)

Clearly, there is something "going on" inside the material of the magnet - something which is expressed as a physical phenomenon, easily observed. But what?

Recall from the preceding page my diagram of a bar magnet surrounded by compasses, placed so as to indicate the magnet's field:

If you were to cut this two-fifths and three-fifths of the way along, remove the middle fifth, and place another compass in the gap, this is what you'd see:

That's right - the compass needle points in the opposite direction from those along the outside length. Compare that with this graphic, also from the preceding page :

Recall that this shows the magnetic field around two flat current-carrying metal strips connected together at one end. Also recall that an almost identical magnetic field is caused by a current-carrying solenoid.

What we have here is extremely good evidence for the suggestion that magnetic effects - even in permanent magnets - are caused by some kind of electrical activity.

To be fair, most textbooks do say this, in essence. The arrangement of electrons within orbitals in atoms, and also their spin, are held to contribute to magnetism in general, and ferromagnetism in particular.

If we accept this (and it makes sense to me), one of the implications is that what are called "magnetic lines of force" are loops, which continue right through the material of a permanent magnet exactly as in a solenoid. They're not two-ended lines or curves "joining the poles". There aren't any poles!

Because of the shape of most magnets, and because their ends are attracted to - or repelled from - the ends of other magnets, it's convenient for practical purposes to think that poles do exist, and are located in the magnet "somewhere near" its ends. In this website, for example, there is a page in which I discuss - without apology - my homemade two-pole electric motor .

My point is, that if we are really to understand electromagnetism, we need to be prepared to think more deeply about what is actually happening, and not allow ourselves to be sidetracked by convenient approximations. Let's move on!

We've been throwing the terms "magnetic field" and "lines of force" around fairly freely, without really specifying what it is we're talking about. There's even a chance that we might use them interchangeably.

Let's make a serious attempt to tighten up our thinking about these matters.

For the moment, put magnetism to one side, and think about electric fields. Have a look at this web-page which introduces the topic very well.

A point charge has an electric field which can be represented by straight lines radiating from the charge. If it's a positive charge, by convention the lines are shown as arrows pointing outwards; if it's negative, the arrows point inwards.

Also shown in the above link are circular equipotential lines. Look at this page from the same site to see more about this, and also the concept of an electric dipole - a pair of opposite electric charges in close proximity to each other.

Now: how many people think that a bar magnet is "somewhat similar", in the way it "works", to an electric dipole? - and, quite frankly, how many textbooks give that impression, at least to some extent?

Far too many, in my humble opinion!

Any number of textbooks or physics websites will tell you that the terms electric field line and electric line of force are interchangeable. The concept is defined as a line (which may be curved) along which a "test charge" will accelerate if placed into an electric field. (If the test charge is negative, it will accelerate toward a positive charge involved in the electric field; and vice versa.)

It's always seemed to me that this is a bit "dodgy", because the suggestion seems to be that this "test charge" behaves as an outside observer, rather than contributing to the field itself! (Shades of Heisenberg's Uncertainty Principle?) However, let's not quibble; there is a certain logic to the definition which can be fairly easily understood. (Presumably, if our "test charge" is small enough, it's not going to contribute much to the overall field; so we can "get away with it" as a reasonable approximation.)

We can visualize one of these (admittedly imaginary) electric lines of force to exist "point to point" between a (real) positive charge and a (real) negative charge; and we can imagine our little "test charge" zooming along this line in one direction or the other in response to a definite physical force.

Okay - so we'll allow the idea of electric lines of force to have some credibility. Now: what about magnetic lines of force?

What are we going to use for an analogous notion of an electric charge? We've already established that magnetic poles don't really exist (unlike electric charges, which really do). So how are we going to come up with a meaningful notion of a magnetic line of force? Where are its ends? In what direction does the force act? Where is our analogue for the "test charge"? Are we going to have to postulate a "test pole"? (I'll reconsider the vexed subject of magnetic monopoles shortly. ) Even if we consider a "test dipole", like a miniature compass needle, the only force it will experience will be a twisting force, or torque - just as in Oersted's experiments.

Check out this web-page for a definition of "magnetic lines of force".

Is it helpful? (Note: I'm not having a dig at this website, or any other source, which quotes a statement like this. They're simply reporting the usual definition.)

If the "magnetic force" (referred to in the above link) is that which makes the compass in Oersted's experiment twitch, then it has some meaning at that level. But is it really helpful, enriching our understanding of something we basically knew already?

Furthermore: the "magnetic lines of force", of which a magnetic field is (supposedly) made up, actually look more like the equipotential lines of an electric field! Are these "magnetic lines of force" actually equipotential lines for something else altogether?

It seems that there is a way out of this quandary after all.

In the previous page, I briefly raised the matter of André Marie Ampère's researches into the interaction between current-carrying wires. He noticed that parallel wires carrying current in the same direction attracted each other, and that parallel wires carrying current in opposite directions repelled each other. (If the wires were at some angle to each other, things were a bit more complicated - but easily handled by appropriate use of trigonometry.)

Also in the previous page, I included this link, which deals with Oersted's work but also mentions Ampère's contribution. Have another look at it now.

In particular, note that if the two wires are each bent into a loop, and placed close to each other, any mutual attraction or repulsion between them can be accounted for in terms of Ampère's observations just as easily as if they had been left straight.

Okay: here we have something which definitely has to do with magnetism and force, but which doesn't require any reference to magnetic poles or magnetic lines of force. We may choose to retain the concept of a magnetic field, around the wires; but the force is not in the "circular direction" (or sense) of this field, but at right angles to it, emanating from the current-carrying wires themselves and cutting across the field's so-called "lines of force".

So, going back to basics - Ampère's simple experiments, and his empirically-found conclusions - finally gives us a way to better understand this otherwise thoroughly confusing matter.

Have a look at this page for the thoughts of someone who has also wrestled with the issue, and - to my mind, at least - has put it all down very neatly and succinctly. (You may bet that I heaved a sigh of relief when I found this on the net, and realized that I wasn't the only person in the world who'd had difficulty in grappling with all this!)

So, we have an account here of magnetic attraction and repulsion without any need for either magnetic poles or magnetic lines of force, as traditionally represented.

Instead, we now have a new vision of something which may be called, for want of a less awkward-sounding term, an "Ampèreic field", which emanates like a cylinder in the form of "Ampèreic lines of force" from the current-carrying wires - and for which the "magnetic lines of force" that we've all known and loved for so long can be viewed as equipotential lines!

Note: I'm not saying that "Ampèrism" explains why these forces exist, any better than an account which cites "magnetic poles" and "magnetic lines of force" does. All I'm saying is that it simplifies the problem by removing unnecessary, confusing "clutter". In traditional terms, I suppose I'm basically suggesting that it's a "better theory"!

Whew!

Having gone through all that, it's not really as though I'm trying to present anything new.

My entire point is that magnetism needs to be better explained, generally speaking, than it often is - especially in some textbooks. If what I've done here can help in that regard, I'm happy. Let's cut away the confusion!

Just while on this topic: here's a web-page which has something to say about the way physics in general, and electromagnetism in particular, is all too often taught and learned. To an extent, I trace my own initial difficulties with the subject back to similar roots. It's a long article, so don't get bogged down in it; for the moment, just get the gist of it by reading the first few screenfuls - you can always return to it later. To those opening remarks, I say a hearty "AMEN"!

Having arrived at what appears to be a neat, logical, even fairly comfortable way of looking at magnetic phenomena, we can all take a deep breath and relax - or can we?

If only.

We've successfully dispensed with "magnetic lines of force" as anything we really need to be concerned about. We've reduced "magnetic poles" to a convenient fiction; they don't really exist, but they're a handy practical approximation to reality when it comes to discussing the operation of useful things like electric motors.

So, if pairs of magnetic poles (north and south) don't really exist, then in no way will an isolated "magnetic monopole" (north or south) exist.

So, what's the problem? Have a look at this web-page.

Oh dear. Someone appears to have - just possibly - thrown a spanner in the works!

Well, do magnetic monopoles exist after all, or don't they?

It's very naughty of them if they do. Officially, they don't - or, at least, they've never been observed. However, unofficially, there are some question marks.

Jump in feet first by having a look at this web-page.

Next, click here. This is part of Tom Bearden's website. Tom Bearden is the man who claims to have successfully developed a Motionless Electromagnetic Generator (MEG), which, if true, looks set to be a way to provide the world with a fabulous new energy source by tapping into the ZPE (zero-point energy). (Have a look at my zero-point energy page to read more.)

What do we make of all this?

I'll be honest: I don't know what to make of it. I'm way out of my depth here. If it is true, it seems to suggest a whole new "dual" universe in which "magnetic currents" may give rise to electric fields of some kind (toroidal? - or some really weird shape like a Klein bottle , perhaps? ), and goodness knows what else.

I'll tell you one thing, though. Unlike the modern "scientific establishment", which is all too eager to pour scorn on anything that threatens to rock its tidy little boat, I'm not about to dismiss any of this out of hand. If it's there, and if it's interesting and/or useful, I want to know more about it, even if it does mean that I may have to make some uncomfortable changes to my view of reality!

How about you?

Just before moving on to closing remarks for this page: here's a link to a web-page in which various characters argue about the pros and cons of magnetism and Ampèreism. (The person promoting Ampèreism is called "Fairfield"; this may or may not be the same person whose name appears to be "Torrance" from the earlier page cited above.) Also, just to liven things up a bit - note that magnetic monopoles rate a mention here!

One good thing about the internet is that is makes possible heated discussion of burning issues, allowing the parties to blow off steam while denying them the ability to physically assault each other!

I'll close this page by "stirring the pot" just a bit more.

In the first "Ampèreism" page referred to above, at one point the author mentions "...magnets, which are self powered, electrically fuzzy, equivalents of air core electromagnets..."

Rather provocative, doncha think? "Self powered"! How are we to interpret that?

Well, there's no doubt that permanent magnets exist. As I've already mentioned, I'm sure we've all played with them. They seem to have some kind of energy bound up in them, which asserts itself in the form of a magnetic field. (Let's not get into that again! )

What "drives" magnets? How do the arrangement and alignment of electrons in certain types of atoms produce this effect, and keep on producing it?

More to the point: how can we make use of this apparently limitless supply of energy?

Well, if my understanding is correct, that's exactly what Tom Bearden claims his MEG does. The basic idea is that by electrical means - running currents in just the correct way through the primary coils of the device - some of the energy is extracted from the permanent magnet at its heart and made available via its secondary coils, with the permanent magnet being "topped up" from the ZPE.

"Too good to be true"?

Respected Nobel Prize-winning physicist Werner Heisenberg (1901-1976), he of the famous Uncertainty Principle (already mentioned earlier in this page), has been quoted as saying:

We could utilize magnetism
as an energy source...

(See this web page to read more.)

You be the judge. Again, I invite you to visit my zero-point energy page to follow these matters up further.

That's it!

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