2 basic magnetism questions

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In summary: Conversely, the magnetic S pole flips around every few hundred years as the molten iron within the Earth's core moves around. In summary, magnetic forces are generated when an oscillating electric and magnetic field is applied to a stationary object. North and south poles are always present, and can be determined by a reference magnet.
  • #1
staballoy
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1. How is magnetism propagated? The descriptions I have read of magnetism explain about spinning electrons and the effects of magnetic fields, but I can find no explanation how magnetic force is propagated. Gravity is explained via GR and the effects of mass/energy on space-time, but I don't find any equivalent explanation for magnetism.

2. How is a north magnetic pole distinguished from a south magnetic pole?

Please note that I am an interested but mathematically illiterate layperson, so I will not be able to follow equations, though I assure you that I appreciate their elegance :smile:
 
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Magnetic effects are often supposed to exist in space, because there is some source of magnetic field (magnet bar, current in a coil, Earth). If nothing moves, the magnetic forces do not change.

But if the magnetic field is due to moving source (like rotating magnet in electromotor, or current in the emitting antenna), EM waves are generated and propagate out of the source. These exert oscillating electric and magnetic forces on everything they hit.

Concerning your second question, north and south poles are always present (they cannot be separated), so you will find out which is which simultaneously. You can do that with a help of reference magnet, for which you know its S and N ends; you find which end of the magnet studied is repulsed from the N pole of your reference magnet and this is defined to be the N pole too (like poles are repulsing each other). The other pole is then S.
 
  • #3
Thank you, but what are the EM waves made of? Aren't photons the carriers of the EM force, but I do not see references to them in discussions of magnetism.

I understand using a reference magnet to determine another magnet's north and south poles, but at some point one might not have such a convenient tool. How do north and south poles differ in characteristics so they attract opposites and repel likes? It appears there is something similar to the positive-negative opposition of electric charges, but I am a thoroughly unschooled layperson, so that may well be a simplistic and misguided assumption.
 
  • #4
Photons are the carriers of electromagnetic field but you have to consider the fact that when EM waves are observed on any macroscopic level, that wave is made of an incredibly large number of photons. What we observe is the averaging over of them in time and space. Particle-like carriers of the electromagnetic field were only first considered when quantum theory was first being developed, which is why any classical field theory or mainstream applications book either won't discuss them or they will be covered/considered in only a smaller portion of the discussion. So, if you were thinking on a particle-particle interaction level, EM waves are photons while if you were dealing with high energy waves, it's arguably a more intuitive convention to consider the EM waves as macroscopic fluctuations of the fields and not particles.

As for the magnets, the names were derived out of conventions mathematically and directionally. Consider the iron filings experiment with a bar magnet and a circular wire loop. If aligned properly, they will give the same pattern in the iron filings. Since the theory at the time this was originally considered said magnetic fields emerge from somewhere, loop away from the source, and return to close the loop and that the magnitude of the force was proportional to the current in the loop. The mathematics characterizing these effects were matched to the right-hand-rule convention in that the magnetic field circulates around a current in the counter-clockwise direction. Thus the magnetic field emerges from the center of the loop, curls around the loop, and back up through the middle. Simply, the 'north' pole of this arrangement was named for where the fields emerge and the 'south' pole is where they return. By the relationships between poles of magnetic sources at the time, the bars were thus given N and S pole names by how they interacted with the current loops.

The attraction principles can be noted simply by creating two identical magnets or current loops with definitive 'poles' and characterizing their interactions with each other. It's interesting to note that the Earth's field is a dipole that changes in time. For the last many thousands of years up to now, the magnetic N pole is located at the geographic south pole.
 
  • #5


1. Magnetism is propagated through the movement of charged particles, specifically electrons. When these charged particles move, they create a magnetic field around them. This magnetic field can then interact with other magnetic fields, causing the propagation of magnetism. In simpler terms, magnetism is propagated through the movement of electrons and their resulting magnetic fields.

2. A north magnetic pole is distinguished from a south magnetic pole based on the direction of the magnetic field lines. Magnetic field lines always flow from the north pole to the south pole, so by observing the direction of these lines, we can determine which pole is north and which is south. Additionally, like poles repel each other and opposite poles attract each other, providing another way to distinguish between the two poles.
 

1. What is magnetism?

Magnetism is a physical phenomenon where certain materials, such as iron, nickel, and cobalt, are attracted to magnets. This attraction is caused by the alignment of magnetic fields within the material.

2. What is a magnetic field?

A magnetic field is an invisible area around a magnet where its force can be felt. It is created by the movement of electric charges, either within the magnet itself or in nearby objects.

3. How do magnets work?

Magnets work by creating a magnetic field that exerts a force on other objects with magnetic properties. This force is strongest at the poles of the magnet, which are where the magnetic field lines converge.

4. Can magnets attract or repel each other?

Yes, magnets can both attract and repel each other. Like poles, such as two north poles or two south poles, repel each other, while opposite poles, such as a north and south pole, attract each other.

5. How can magnets be used in everyday life?

Magnets have a wide range of uses in everyday life. They are used in speakers, motors, credit cards, and even medical devices. They are also used in compasses to help with navigation and in magnetic jewelry for healing purposes.

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