Calculate Force Between Neodymium Magnets

In summary: Forceinitial x (initial distance / new distance)^2If you want to calculate the force between two magnets, you would need to use an equation that takes into account their shape, size, and strength.
  • #1
eddybob123
178
0
hi, I was wondering if there is an equation out there that let's you calculate the force between two neodymium magnet. thanks, i would really appreciate an answer.
 
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  • #2
eddybob123 said:
hi, I was wondering if there is an equation out there that let's you calculate the force between two neodymium magnet. thanks, i would really appreciate an answer.
If there is an equation, this must also consider the shape of the magnets. Two magnets with same mass and grade will have different "center of magnetism".

Say you have two cube magnets, N40, with the volume of 1cm^3. These will not get closer to the center than approx 5mm. To pull them apart require a given force.

Say you have two square magnets measuring 1mm x 31.6mm x 31.6mm (1cm^3), and you put them together surface to surface, it will require greater force to separate them. If you put them together edge to edge, it will require less force to separate them.
In addition, there will be different force required between magnetized through thickness, and through length. Surface to surface, and magnetized through length will allow the magnetic flux to have a tighter and more dense flux loop, which also require even greater force to separate.

However, at greater distance both shapes will attract practically equal for both shapes.

I have done a lot of experiments with this.

Vidar
 
Last edited:
  • #3
eddybob123 said:
hi, I was wondering if there is an equation out there that let's you calculate the force between two neodymium magnet. thanks, i would really appreciate an answer.

Finding the answer is more detailed than I think you are expecting. The force will depend on the shapes, sizes, and strengths of the magnets, as well as their relative position and orientation. The equations that describe the interacting fields are Maxwell's equations, but they have to be applied to a specific problem.
 
  • #4
Let's just say that the magnets are cylindrical and the face is 2 cm in diameter, and the height is 5 cm.
 
  • #5
eddybob123 said:
Let's just say that the magnets are cylindrical and the face is 2 cm in diameter, and the height is 5 cm.

The magnetic force is generally exponential to distance. If you know the force at 10cm distance, the force is increased 4 times at 5cm distance.

The general equation would be this: Forceinitial x (initial distance / new distance)^2
Example:
Initial distance Di is 10cm.
New distance Dn is 7cm
Initial force Fi is 2N
New force Fn is unknown

Fn = Fi(Di / Dn)^2 =
2N(10cm/7cm)^2 = 4.08N


Vidar
 
  • #6
But assume the magnets are stationary?
 
  • #7
Low-Q said:
The magnetic force is generally exponential to distance.

Magnet-magnet interactions like the OP is asking about are dipole-dipole interactions and go like 1/r3, not exponential.

BBB
 
  • #8
How do you get those number?
 

FAQ: Calculate Force Between Neodymium Magnets

How do you calculate the force between two Neodymium magnets?

To calculate the force between two Neodymium magnets, you can use the following formula: F = (μ0 * m1 * m2) / (4π * d^2), where F is the force in Newtons, μ0 is the permeability of free space, m1 and m2 are the magnetic moments of the two magnets, and d is the distance between the two magnets.

Can you use this formula for any shape or size of Neodymium magnets?

Yes, this formula can be used for any shape or size of Neodymium magnets as long as the magnetic moments are known and the distance between the magnets is measured accurately.

How does the force between Neodymium magnets change with distance?

The force between Neodymium magnets follows an inverse square law, meaning that as the distance between the magnets increases, the force decreases exponentially. This is due to the fact that the magnetic field strength decreases with distance.

Can the force between Neodymium magnets be repulsive?

Yes, the force between Neodymium magnets can be both attractive and repulsive depending on the orientation of the magnets. If the North poles of both magnets are facing each other, the force will be repulsive. If the North and South poles are facing each other, the force will be attractive.

How can I measure the force between Neodymium magnets?

To measure the force between Neodymium magnets, you can use a force gauge or a spring scale. Place the magnets a known distance apart and slowly move them closer together until they attract or repel each other. The force measured at this distance will be the force between the magnets.

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