What happens to magnetic fields when poles are near each other?

In summary, the conversation is about the effects of same and different magnetic poles being in close proximity to each other for an extended period of time. It is explained that in most cases, nothing significant happens to the magnets themselves, but warming a magnet can reduce its ability to maintain its magnetic properties. The idea of a six magnet vehicle engine is proposed, but it is stated that discussing PM machines is against site guidelines and the thread is locked.
  • #1
Newtype
39
0
What happens when same magnetic poles (i.e., NN or SS) are next to each other for say an hour or more - will the magnetic fields of those magnets become weaker or stronger?

What happens when different magnetic poles (i.e., NS or SN) are next to each other for say an hour or more - will the magnetic fields of those magnets become weaker or stronger?

Please provide formulas and examples, thank you.
 
Physics news on Phys.org
  • #2
Simple question, complicated answer:

For practical purpose, in the attracting pole case, nothing interesting happens. The field lines merge and the two smaller magnets effectively behave as a larger magnet. For practical, permanent magnets, usually nothing happens to the magnets themselves. (more on this in a moment).

In the repelling case, the field lines bend away from each other, and the magnets create a repelling force. Again, in most cases, nothing interesting happens to the magnet.

Okay, now let's step away from the "most cases" qualifier.

Magnets have two key properties: remnance and coercivity. Remnance is a description of how intense a field the magnet produces. Coercivity is a description of how hard it is to demagnetize the material (actually, to 50% reverse-magnetize it, but for our purposes we can be a little sloppy). Now, as long as we don't exceed the coercivity, nothing will happen - and for various measurements we have done, time is not a function in the equation. Leave it for an hour, two hours...there will be no useful difference. Temperature is a big factor - warming a magnet up can reduce the coercivity.

Having said all that, your typical rare-earth magnets have very high coercivities, and are really hard to demag with another permanent magnet. Alnico magnets, on the other, are notoriously easy to flip or change.

No formulas, but there are some examples there. Hope it helps.
 
  • #3
Thank you, MagnetDave. So basically I could design a six magnet vehicle engine. This would be a good way to reduce global warming and dependence on oil. Here's how this machine I wrote up the plans for works: Two inner moving bar magnets (mounted in frames) repel each other along tracks. Next, two outer stationary bar magnets repel the two inner moving bar magnets back to each other. This process works infinitely. While the inner moving bar magnets are moving they each turn a gear. Each of those gears turns an axle and each of those axles turns a horseshoe magnet inside of a coil of wire generating electricity. Thus electricity can be produced forever using this machine. It would require diodes to convert the alternating currents into direct currents. With power amplifiers this machine might possibly electrically power a house (each house might have one of these generators and modified if desired) and a vehicle (a person might have his/her car powered by one of these generators). Would this six magnet vehicle engine work? If so, how long?

NS---SN---NS----SN
___Gear__Gear
____Axle__Axle
____NS___SN
____Coil__Coil
 
Last edited:
  • #4
I coincide with above explanations. If we take two bar magnets near to each other, then like magnet poles repel each other and dislike poles attract each other.-narasimha charyulu
 
  • #5
Newtype said:
So basically I could design a six magnet vehicle engine. This would be a good way to reduce global warming and dependence on oil. Here's how this machine I wrote up the plans for works: Two inner moving bar magnets (mounted in frames) repel each other along tracks. Next, two outer stationary bar magnets repel the two inner moving bar magnets back to each other. This process works infinitely. While the inner moving bar magnets are moving they each turn a gear. Each of those gears turns an axle and each of those axles turns a horseshoe magnet inside of a coil of wire generating electricity. Thus electricity can be produced forever using this machine. It would require diodes to convert the alternating currents into direct currents. With power amplifiers this machine might possibly electrically power a house (each house might have one of these generators and modified if desired) and a vehicle (a person might have his/her car powered by one of these generators). Would this six magnet vehicle engine work? If so, how long?

NS---SN---NS----SN
___Gear__Gear
____Axle__Axle
____NS___SN
____Coil__Coil

One word.

No.

Discussion of PM machines is against site guidelines.

Thread locked.
 

1. What is a magnetic field and how does it work?

A magnetic field is a region in space where a magnetic force is exerted on charged particles. It is created by the movement of electrically charged particles, such as electrons. When these charged particles move, they create a force that can attract or repel other charged particles, depending on their orientation.

2. How do magnetic fields interact when poles are near each other?

When magnetic poles are near each other, the magnetic fields interact with each other. This occurs because the magnetic field lines of each pole are attracted to the opposite pole and repelled by the same pole. This causes the magnetic fields to either attract or repel each other depending on the orientation of the poles.

3. What happens to the strength of a magnetic field when poles are close together?

When poles are close together, the strength of the magnetic field increases. This is because the magnetic field lines from each pole are closer together, resulting in a stronger force between the poles. The closer the poles are, the stronger the magnetic field will be.

4. Can two magnetic poles cancel each other out?

Yes, two magnetic poles can cancel each other out. This occurs when the poles are of equal strength and are aligned in opposite directions. When this happens, the magnetic fields will cancel each other out, resulting in a weaker overall magnetic field.

5. Is there a limit to how close magnetic poles can be to each other?

Yes, there is a limit to how close magnetic poles can be to each other. The closer the poles are, the stronger the force between them becomes. However, if the poles are brought too close together, the force can become so strong that the poles will snap together and become one magnet. This limit is known as the Curie temperature and varies depending on the type of magnet.

Similar threads

  • Electromagnetism
Replies
6
Views
525
Replies
15
Views
1K
Replies
8
Views
932
Replies
2
Views
704
Replies
6
Views
1K
Replies
27
Views
984
Replies
8
Views
955
Replies
19
Views
968
  • Electromagnetism
Replies
4
Views
9K
Replies
3
Views
596
Back
Top