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Building an electro magnet 
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#1
Apr2613, 09:51 AM

P: 39

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 [itex]\vec{F}=\frac{B}{µ0}*A[/itex] A= cross sectional area = 0,002*1/100 M^2 B = Magnetic Force µ0(permeability in vacuum) = 4[itex]\pi[/itex]*10^17 B_gap(x) =[itex]\frac{µ0*I*N}{\frac{l_j}{µj}+2x}[/itex] 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? 


#2
Apr2613, 01:38 PM

Mentor
P: 3,926

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 currentlimiting devices. You're basically trying to build a controlled short circuit here.... Resistors and fuses are your friends. 


#3
Apr2613, 03:00 PM

P: 39

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=[itex]\frac{b}{µ0}*A[/itex] Where A =0,002*1/100 <=> 5 =[itex]\frac{b}{µ0}*A[/itex] <=> B =3.14159*10^11 Then i solve N using the other equation and then i get 1001 winding. 


#4
Apr2613, 04:25 PM

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Thanks
PF Gold
P: 6,723

Building an electro magnet
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) 


#5
Apr2613, 04:27 PM

P: 39

Yeah... the metal plate i bended needed to be 2mm thick, and the lengt of it is 1cm..
A is Crosssectional area in M^2 


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