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Electricity Doesn't Flow Through Wire

The magnet in a compass aligns with the earth's magnetic field, maybe that's what you were thinking about.

I thought magnets were to do with particle spin, and the uniform alignment thereof? Unmagnetised material has these spins randomised. But I can't remember clearly, I'm sure someone more current (I know that one's been done but still!) with the theory will add/correct.
 
John Phillips said:
That's the reason behind the somewhat convoluted "not disproved" double-negative language you were quite naturally wondering about in the post you commented on and in my post assuming what that one referred to. This makes me think that perhaps in a forum I ought to drop "correctness" for the sake of clarity.
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That stuff is vaguely familiar to me. Even on a Social Sciences Degree and choosing all possible Politics options.. (partly to avoid the maths and stats which infested sociology and psychology).. I was confronted with stuff about, I think..Karl Popper and the Theory of Falsification.. which at least in my mind is interlaced with something about 'Disproving the Null Hypothesis' or somesuch. Trouble is this stuff falls into the same part of my consciousness as does much mathematics. As such I tend to understand it whilst it is explained, but lose it within seconds. It just doesn't stick.
 
I'm not sure of the question but magnetism comes down to spinning electrons. I did find a good explanation by one of my favourite lecturers (and Nobel prize winner) Feynman but it has quite a bit of maths and I remember you telling us that you didn't study Chemistry beyond ONC as you couldn't do the maths.

Think of an old penny made of copper. If you look from one side you see a head and the other a tail but both are the same penny made of copper. You can think of the electromagnetic force in a similar fashion. They are both the equivalent force but appear as either a magnet or a charge depending how you look at it. (I'm going to get shot down for this explanation but it gives an idea without any maths). Thats why you can get a magnetic field from electrons and an electric field from magnets.

Not all elements exhibit strong magnetic fields but quite a few have weak and very weak fields.

When I taught science I held a large iron rod and aligned it in the Earth’s magnetic field. First I showed that the rod didn't exhibit any magnetism as both ends of a compass were attracted to each end. I then whacked the end of the rod aligned with the Earth's field with a hammer and showed that the rod was now magnetised as it would both attract and repel the compass magnet. I could then demagnetise the rod by whacking the end with the rod rotated 90 degrees to the Earth's field.

Science is fun no?

DV

PS Linky to the lecture https://www.feynmanlectures.caltech.edu/II_34.html
 
Darth Vader said:
I'm not sure of the question but magnetism comes down to spinning electrons. I did find a good explanation by one of my favourite lecturers (and Nobel prize winner) Feynman but it has quite a bit of maths and I remember you telling us that you didn't study Chemistry beyond ONC as you couldn't do the maths.

Think of an old penny made of copper. If you look from one side you see a head and the other a tail but both are the same penny made of copper. You can think of the electromagnetic force in a similar fashion. They are both the equivalent force but appear as either a magnet or a charge depending how you look at it. (I'm going to get shot down for this explanation but it gives an idea without any maths). Thats why you can get a magnetic field from electrons and an electric field from magnets.

Not all elements exhibit strong magnetic fields but quite a few have weak and very weak fields.

When I taught science I held a large iron rod and aligned it in the Earth’s magnetic field. First I showed that the rod didn't exhibit any magnetism as both ends of a compass were attracted to each end. I then whacked the end of the rod aligned with the Earth's field with a hammer and showed that the rod was now magnetised as it would both attract and repel the compass magnet. I could then demagnetise the rod by whacking the end with the rod rotated 90 degrees to the Earth's field.

Science is fun no?

DV

PS Linky to the lecture https://www.feynmanlectures.caltech.edu/II_34.html
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Actually, I never came across any chemistry which required maths which was beyond me. It was the course which required the Maths. But let's not labour the point.

Thanks DV but I already knew the practical stuff about hitting things etc. I also have a laymans understanding of the relationship between coils and moving conductors etc. Also, in a very real and practical sense, it doesn't matter much what causes a permanent magnet to be a permanent magnet. So, if it is down to spinning electrons, I'll take that. That really isn't my question.

Let me put it this way... If a permanet magnet picks up a piece of non magnetised material, and then holds on to it.. then surely some energy is involved? So the question becomes.. where does that energy come from? It seems to me that the energy does not reside in the magnet. It is not, in other words..some sort of 'battery', as permanent magnets do not generally 'run out of magnetism', unless maybe heated, or subjected to shock or whatever.
So.. if the 'energy' employed by the magnet to do it's thing does not come from within the magnet.. then where from?
That is why I have always understood permanent magnets to be effectively devices which somehow interact with the Earth's magnetic field, and that is where their magnetic 'energy' derives from. Hence my question. What happens if you take a permanent magnet away from the influence of Earths (or any other) magnetic field?

If I have this completely wrong..where does the 'energy' of a permanent magnet come from..and why for practical purposes does it not run out?
 
Mullardman said:
Actually, I never came across any chemistry which required maths which was beyond me. It was the course which required the Maths. But let's not labour the point.

Thanks DV but I already knew the practical stuff about hitting things etc. I also have a laymans understanding of the relationship between coils and moving conductors etc. Also, in a very real and practical sense, it doesn't matter much what causes a permanent magnet to be a permanent magnet. So, if it is down to spinning electrons, I'll take that. That really isn't my question.

Let me put it this way... If a permanet magnet picks up a piece of non magnetised material, and then holds on to it.. then surely some energy is involved? So the question becomes.. where does that energy come from? It seems to me that the energy does not reside in the magnet. It is not, in other words..some sort of 'battery', as permanent magnets do not generally 'run out of magnetism', unless maybe heated, or subjected to shock or whatever.
So.. if the 'energy' employed by the magnet to do it's thing does not come from within the magnet.. then where from?
That is why I have always understood permanent magnets to be effectively devices which somehow interact with the Earth's magnetic field, and that is where their magnetic 'energy' derives from. Hence my question. What happens if you take a permanent magnet away from the influence of Earths (or any other) magnetic field?

If I have this completely wrong..where does the 'energy' of a permanent magnet come from..and why for practical purposes does it not run out?
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I don't know, but whatever it is that holds an iron bar (or anything solid) together, is the same as holds a magnetic iron bar together. Not sure if that is "energy" since it never seems to run out. The magnetic property is thought to be about how the electrons are aligned or arranged. I am not sure that any additional "energy" is required.
 
Mullardman said:
Actually, I never came across any chemistry which required maths which was beyond me. It was the course which required the Maths. But let's not labour the point.
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Thats correct up to ONC/'A' Level but the next step upwards HNC/degree does. I remember my first term at Uni reading Chemistry and we had 4 ladies in the class. In that first term we had Schrödinger’s wave equation and quantum mechanics both involved quite complex Calculus. I don't know if your ONC syllabus was the same as mine but the endorsement (optional) maths paper went into both differential and integral calculus in preparation for the degree-level work of HNC/BSc. Oh and those 4 ladies? In term 2 there was only one remaining............

Cheers,

DV
 
Darth Vader said:
Thats correct up to ONC/'A' Level but the next step upwards HNC/degree does. I remember my first term at Uni reading Chemistry and we had 4 ladies in the class. In that first term we had Schrödinger’s wave equation and quantum mechanics both involved quite complex Calculus. I don't know if your ONC syllabus was the same as mine but the endorsement (optional) maths paper went into both differential and integral calculus in preparation for the degree-level work of HNC/BSc. Oh and those 4 ladies? In term 2 there was only one remaining............

Cheers,

DV
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and your point is ?
 
What does a student’s gender have to do with studying science or math?

joe
 
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Mullardman said:
Let me put it this way... If a permanet magnet picks up a piece of non magnetised material, and then holds on to it.. then surely some energy is involved? So the question becomes.. where does that energy come from?
Click to expand...

You are thinking in classical physics and you need modern physics to answer your question. The simplest way I can put this (and again I'll be knocked down) is that the force carriers (photons in our case) can 'borrow' energy from the Universe for an infinitesimally small time and then pay it back. In classical physics outer space apart from the odd item is empty however at the quantum-level (modern physics) its a boiling cauldron of activity with sub-atomic particles continuously being created and then annihilated. Stephen Hawking used this idea to postulate Hawking radiation and how a black hole might after time shrink in size and go bang.

Science is really interesting,

DV
 
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