Electromagnets Range: Comparing Neodymium & Electromagnets

In summary, the conversation is about how to calculate the force and distance between two magnets, one being a permanent magnet and the other being an electromagnet. The formula for calculating this force is given as F = Magnetic Permability constant * S1 * S2 / r2, where S1 and S2 are the strengths of the poles and r is the distance between them. The discussion also touches on the issue of friction and the complexity of magnet calculations. The participants are unsure about the validity of the inverse square law for magnets and suggest seeking help from a physics forum for a more accurate answer.
  • #1
Cocacolacan
15
0
Hello,
Let's say I have a neodymium magnet with 20 lbs of force, and an electromagnet with 200 lbs of force. Is there a way I could figure out the maximum distance that they would attract each other?
 
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  • #2
You would have to specify the shapes and dimensions and specify a threshold for the attraction.
 
  • #3
circular magnets, 2" diameter (both of them) and air is in between them, and what is the threshold of attraction?
 
  • #4
Threshold of attraction is the very low number you arbitrarily pick to be zero attraction. Are you an EE student?
 
  • #5
No I'm not, I will be studying to be a physicist or biomedical engineer next year though (going into college next year).

And I'm still not getting this threshold of attraction, have any links?
 
  • #6
What do you mean the maximum distance they attract each other? The range is infinite. Do you mean when Fmag can overcome the friction of the magnet on the table?
 
  • #7
okay, let's rephrase. So I have two permanent magnets, one is pulling 30 lbs and the other is pulling 20 lbs. There's a .5 coefficient of friction, and they're opposite poles. How would I figure out the distance at which the magnets would overcome the coefficient of friction and pull each other together?
 
  • #8
No, I did not. I'm hoping my AP Physics teacher might have an answer, he is usually so busy, but now after the test he might be free.
 
  • #9
As I understand it, magnet/electromagnet calculations can get extremely complicated, as they depend on the shapes of the poles, the angle they make with each other, the distribution of magnetism over the surface of the objects, and other things too. I believe there are some simplified scenarios for which you can get an orcder of magnitude approximation, as explained by the wiki article (google 'Force between two magnets'), but beyond that, you might have to resort to Finite Element Analysis, or something equivalent.
 
  • #10
Okay, I have an equation.

If you're going through air between the magnets,
the equation will be

F=Magnetic Permability constant*S1*S2/r2

That is, (4*pi)×10−7 N·A−2 times the strength of the pole of interest number one times the strength of the pole of interest number two divided by the distance that separates them squared.

You can put it onto a calculator, set R as X, and watch the force drop off into oblivion.

Hope this helps someone in the future.
 
  • #11
Cocacolacan said:
Okay, I have an equation.

If you're going through air between the magnets,
the equation will be

F=Magnetic Permability constant*S1*S2/r2

That is, (4*pi)×10−7 N·A−2 times the strength of the pole of interest number one times the strength of the pole of interest number two divided by the distance that separates them squared.

You can put it onto a calculator, set R as X, and watch the force drop off into oblivion.

Hope this helps someone in the future.

There is nothing clear about any of this. Magnets, for one, do not obey an inverse square law. And you've said nothing about this source of friction.
 
  • #12
Alright then, what do magnets follow? And wouldn't friction be something that would be dealt with later? As I would find a force on the graph that would equal the normal force of the magnet?

Does anyone know an answer to this question, it is driving me nuts. (How to find the force between two magnets across a distance that are interacting in air?)

The magnets are both circular, one is an electromagnet and the other is a permanent magnet.

Would this question be better in the physics section of the forum?
 
Last edited:
  • #13
Phrak said:
There is nothing clear about any of this. Magnets, for one, do not obey an inverse square law. And you've said nothing about this source of friction.

agreed
 

What are electromagnets?

Electromagnets are temporary magnets created by passing an electric current through a wire. The magnetic field is only present when the current is flowing through the wire.

What is the difference between neodymium and regular electromagnets?

Neodymium magnets are permanent magnets made from a combination of neodymium, iron, and boron. They are much stronger than regular electromagnets, which rely on an electric current to create a magnetic field.

What is the range of neodymium and electromagnets?

The range, or strength, of a magnet is measured in units called gauss or tesla. Neodymium magnets have a much higher range than regular electromagnets, with a maximum strength of around 1.4 tesla compared to 0.1 tesla for an electromagnet.

Which type of magnet is better for industrial use?

It depends on the specific application. Neodymium magnets are stronger and can be used for lifting heavy objects or in motors. However, electromagnets are more versatile as their strength can be adjusted by changing the electric current, and they can be turned on and off as needed.

Can an electromagnet be made as strong as a neodymium magnet?

No, an electromagnet cannot be made as strong as a neodymium magnet. The strength of an electromagnet is limited by the amount of current and the size of the wire, while neodymium magnets have a fixed strength based on their composition.

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