Strength of an electromagnet

If the object is .5kg or less, you can just use the following:B = 4\pi M * .5 kg/m^2 = 2.25T in Teslas
  • #1


Science Advisor
So, I'm playing around with electromagnets right now and I was wondering how to calculate (or determine experimentally) the approximate strength of the electromagnet. What I'm doing right now is using the formula for a solenoid, [tex]B=\mu_o N i[/tex] and adding the constant for whatever material is in the center (iron right now, so x200). The thing is, for the magnet I have sitting in my room right now I have i>.250mA (highest rating my multimeter goes to) which is giving me a magnetic field strength of 1.13T. So, this is kind of ridiculous and I don't think this is what I'm really getting so here lies the problem:

Because I wrapped the wire around multiple times, does the distance from the iron core factor into the equation? It makes sense to me that each successive wrap will have less effect than the previous one. Also, I don't mind experimentally determining the value, but I'd like to have it in Tesla. Any idea how to convert data if I lift, say, a .5kg object into a tesla value at the surface of the magnet? Thanks for any help provided!
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  • #2
In gaussian units, [tex]F=2\pi M^2A[/tex] is the lifting force, where M is the "magnetization" of the magnet and A is the common contact area in cm.
With iron in contact, [tex]B=4\pi M[/tex] (in gauss) at the end of the magnet.
If iron is not in contact, B at the end is [tex]2\pi M[/tex].
  • #3
I got this equation from a few friends and to be honest i don't even fully understand it myself yet but i hope it helps

1. The force generated by an electromagnet is approximately:
F = mu_r^2 * mu_o * N^2 * I^2 * A / (2 * L^2), where
mu_r is relative magnetic permeability of the magnet core.
mu_o is the permeability of freespace (4*pi* 10^-7)
N is the number of turns of wire in the magnet coil
I is the current in the coil, in amperes
A is the cross-sectional area of the core (in m^2)
L is the magnetic circuit length, including the object being lifted.

2. Since most iron saturates at about 1-2 Tesla, you have to check the field strength with this formula:
B = mu_r * mu_o * N * I / L, in Teslas

What is an electromagnet?

An electromagnet is a type of magnet that is created by running an electrical current through a wire. The magnetic field generated by the current causes the wire to act like a magnet.

What factors affect the strength of an electromagnet?

The strength of an electromagnet is affected by the amount of current flowing through the wire, the number of turns in the wire, and the material and shape of the core used. Increasing any of these factors will result in a stronger electromagnet.

How can I increase the strength of an electromagnet?

To increase the strength of an electromagnet, you can increase the amount of current flowing through the wire, add more turns to the wire, or use a core made of a stronger magnetic material.

What are the applications of electromagnets?

Electromagnets have a wide range of applications, including in electric motors, generators, speakers, MRI machines, and particle accelerators. They are also used in everyday objects such as doorbells, refrigerators, and computer hard drives.

Are there any limitations to the strength of an electromagnet?

Yes, there are limitations to the strength of an electromagnet. The wire used must be able to handle the current without overheating, and the core material must not reach its magnetic saturation point. Additionally, the magnetic field produced by the electromagnet decreases with distance from the core, so the strength of the magnet is limited to a certain distance.

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