How do I calculate the repelling Force of an Electromagnet?

  • Context: Undergrad 
  • Thread starter Thread starter jason Kenedy
  • Start date Start date
  • Tags Tags
    Electromagnet Force
Click For Summary

Discussion Overview

The discussion revolves around calculating the repelling force of an electromagnet, specifically focusing on determining the current required to achieve a field strength capable of repelling a force of 2000 Newtons. The conversation includes theoretical considerations and practical applications related to electromagnet design.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant seeks to calculate the current needed for an electromagnet to repel a force of 2000 Newtons.
  • Another participant suggests a field strength of 400000 A/m but notes that this value depends on factors such as the shape and dimensions of the magnets involved.
  • A participant mentions finding a formula that allows for reverse solving for the pole strength of the electromagnets.
  • There is a question about the meaning of variables m1 and m2 in the context of the formula, with a suggestion that they may refer to pole strengths rather than masses.
  • A detailed explanation of energy density and force calculation in relation to electromagnets is provided, including the formula for energy density and the relationship between energy and force.
  • A query is raised regarding the size of the cross-sectional area (A) used in the calculations.

Areas of Agreement / Disagreement

Participants have not reached a consensus, as there are multiple viewpoints regarding the calculations and factors influencing the electromagnet's performance. Uncertainties remain about the definitions and variables used in the formulas discussed.

Contextual Notes

Limitations include the need for specific definitions of variables and assumptions regarding the dimensions and shapes of the magnets, which are not fully addressed in the discussion.

jason Kenedy
Messages
2
Reaction score
0
Hello everyone, I am working on a project and I am trying to figure out the formula to use. My goal is to calculate the amount of current needed to create an electromagnet with a strong enough field strength to repel a force of 2000 Newtons.
thank you
 
Physics news on Phys.org
jason Kenedy said:
My goal is to calculate the amount of current needed to create an electromagnet with a strong enough field strength to repel a force of 2000 Newtons.
The short answer is: 400000 A/m.
But of course it depends on:

* What kind of magnet ( shape ).
* Dimensions of the magnet and the other magnet to be repelled. ( for example unmagnetized iron will always be attracted ).

So you need to fill out "All known data:".
 
Last edited:
Thanks. Actually I just found this formula. I can reverse solve for m1 and m2 which is the pole strength of each electromagnet I would be using for the project.
4f895116f8bde4cf60497d348294918b.png
and then solve for the current I need.
 
I don't recognize this formula. What is m1 and m2: Masses, or?

Say you have two magnets kept apart with a distance, s. The cross section areas of the magnets are A. The energy density within the airgap will be

Edens = ½*B*H [ J/m3 ] ( = ½*μ0*B2 )

The energy in the airgap will be E = ½*B*H*Volumeairgap = ½*B*H*s*A

Now, you can find the force: F = dE/ds = ½*B*H*A.

But what is the size of A?
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K