How can I optimize my electro magnet?

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Discussion Overview

The discussion centers around optimizing an electromagnet to achieve a pulling force of 5N. Participants explore calculations related to magnetic force, coil windings, and the properties of materials used in the construction of the magnet.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant describes their approach using S37 iron for a horseshoe magnet and provides a formula for converting Newtonian force to magnetic force, including specific values for cross-sectional area and other parameters.
  • Another participant questions the interpretation of "too extreme" regarding voltage and suggests considering the inductance of the coil alongside resistance for a complete understanding of the setup.
  • A participant presents a simplified calculation assuming the magnetic force from the iron core equals that in the gap, leading to a different estimate of required windings (1001) for the electromagnet.
  • There is a request for clarification on the units used in the cross-sectional area calculation, indicating potential confusion about the expression provided.

Areas of Agreement / Disagreement

Participants express differing views on the calculations and assumptions made regarding the electromagnet's design, with no consensus reached on the optimal number of windings or the interpretation of voltage requirements.

Contextual Notes

Some calculations depend on assumptions about the magnetic force distribution and material properties, which may not be fully resolved. The discussion also highlights potential ambiguities in unit conversions and expressions used by participants.

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Hey guys..

I trying to build an magnet which can pull an object with 5N..

I am using S37 as my the iron for my horseshoe magnet,

And been using this formula to convert Newtonian Force to magnetic force

\vec{F}=\frac{B}{µ0}*A

A= cross sectional area = 0,002*1/100 M^2
B = Magnetic Force
µ0(permeability in vacuum) = 4\pi*10^-17

B_gap(x) =\frac{µ0*I*N}{\frac{l_j}{µj}+2x}
l_j: the length of horseshoe = 2 CM
µj: permeability of Steel37.. Can't find it using google.. :(
x: airgap distance between each legs and the materiel it should attract. = 0,002m

I am using 1 A, I tested my calctulation with 3N, which using my calculation says that i need 600 windings, but i seem to extreme..

The reason why i think this is not true is because 600 winding => 2 (0.002 + 0.01)*600 M copper wire=> R=0,079 ohm => V =0,079V..Is it too extreme?
 
Last edited:
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215 said:
Is it too extreme?

Not sure what you mean by "too extreme"... are you thinking that the voltage required seems awfully low? I haven't checked your calculations, but it doesn't take much voltage at all to drive one amp through a length of copper wire. You will probably have to consider the inductance of the coil as well as the resistance of the wire to completely understand how your setup will work.

You could do worse than actually wiring up an electromagnet with some number of turns, see how close your calculations are. But if you do... Don't use a voltage high enough to hurt yourself or anything near you, and think about your current-limiting devices. You're basically trying to build a controlled short circuit here... Resistors and fuses are your friends.
 
My caluculation is kinda simple..

Assume that the magnetic force from the iron core is the same as the one in the gap.

I know that I need the magnet to pull 5N

Which means that
F=\frac{b}{µ0}*A

Where A =0,002*1/100
<=>
5 =\frac{b}{µ0}*A
<=>
B =3.14159*10^-11

Then i solve N using the other equation and then i get 1001 winding.
 
A = 0.002 * 1/100 is a rather curious expression. What units does it have? How did you calculate it?
(your comma is my decimal point)
 
Yeah... the metal plate i bended needed to be 2mm thick, and the lengt of it is 1cm..
A is Cross-sectional area in M^2
 
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