Magnetic Force of identical shaped box bar magnets

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Discussion Overview

The discussion revolves around the magnetic force between identical box bar magnets, specifically addressing how the magnetic force weakens with distance and the mathematical principles that govern this behavior. Participants explore theoretical concepts, mathematical formulations, and practical implications related to magnetism.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant expresses confusion about how the magnetic field from a magnet weakens with distance, asserting that the magnetic field is consistent and does not weaken.
  • Another participant suggests a qualitative approach by comparing the force of a refrigerator magnet at a distance of 10 meters, implying that the force diminishes with distance.
  • There is a challenge regarding the terminology used, with a participant questioning the concept of a "bar magnet with magnetic field b."
  • Some participants reference the Biot-Savart law and Ampere's law to explain the relationship between magnetic field strength and distance, noting that the magnetic field is inversely proportional to distance.
  • Concerns are raised about the application of the Biot-Savart law, particularly regarding the speed of electrons and the necessary information to determine the repelling or acting force of a magnet.
  • One participant mentions the inverse square proportionality of gravitational force, suggesting a parallel to the diminishing force between magnets as distance increases.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the nature of magnetic fields and their behavior with distance. Some assert that the magnetic field does weaken, while others maintain that it remains consistent. The discussion remains unresolved with multiple competing views present.

Contextual Notes

Participants reference various laws and concepts in magnetism, but there are limitations in the discussion, such as missing assumptions about the magnets' properties and the specific conditions under which the magnetic forces are being analyzed.

dm164
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I am having a problem with my understanding. I could be incorrect, but I think that the magnetic field emitted from a magnet is consistent and doesn't weaken at points further away. Then could someone explain how magnet force weakens with distance. I would also like to know the math so here is a problem I created.

Say I have two identical shaped box bar magnets with dimensions (l,w,d) and mass m, and magnetic field b/

The face of w*d is the side that is directed at each magnet. (ie wxd of magnet_a faces w*d of magnet_b)

Variable x is the distance between the two magnets.

So, how can I figure the forces at x.Sorry, I accidently put this in wrong forum
 
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Take a refrigerator magnet and hold it 10 meters from a refrigerator. Is there much force? That should tell you something qualitative about the force vs. distance.

There is no such thing as a "bar magnet with magnetic field b" so the second part has no answer.
 
@Vanadium you are no help. I didn't say if magnets force get weaker I said how does it.

Also then, why are magnets rated in Teslas. Such as Neodymium which is 1.2-1.6 Tesla at poles.
 
dm164 said:
@Vanadium you are no help. I didn't say if magnets force get weaker I said how does it.

dm164 said:
I think that the magnetic field emitted from a magnet is consistent and doesn't weaken at points further away

When you make up your mind, we can talk.
 
dm164 said:
Then could someone explain how magnet force weakens with distance. I would also like to know the math so here is a problem I created.
Use the Biot-Savart law (http://en.wikipedia.org/wiki/Biot_savart) or Ampere's law (http://en.wikipedia.org/wiki/Ampere_law) to express the magnetic field as fuction of distance, you will find that the magnetic field is inversely proportional to distance.

To find the magnetic force, you will then need to use the Lorentz force applied on a charged particle moving in a magnetic field (http://en.wikipedia.org/wiki/Lorentz_force).
 
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Bio Savart works with a moving charge, but I don't know the speed the electrons. What formulas can be used to determine the repelling or acting force of magnet. And what information do I need about a magnet's strength that will help me.
 
dm164 said:
Bio Savart works with a moving charge, but I don't know the speed the electrons. What formulas can be used to determine the repelling or acting force of magnet. And what information do I need about a magnet's strength that will help me.

Wow! Your problem is now getting serious but check this out http://en.wikipedia.org/wiki/Magnetic_field
 

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