What is the Formula for Determining the Strength of an Electromagnet?

In summary, the strength of an electromagnet depends on various factors such as the number of coils, current, and voltage. The core material also plays a significant role in determining the strength. A mathematical formula for determining the strength of an electromagnet involves the permeability of the core and the current in the wire. The geometry of the situation, including the orientation of the object being affected, also affects the strength. The initial permeability and maximum permeability of the core material must be taken into account when calculating the strength. The number of coils is typically measured per unit length, and the length of the core also affects the strength. The diameter of the core may also have an impact on the strength of the electromagnet.
  • #1
mrjeffy321
Science Advisor
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I think I remember there being a formula to determine the Strength of an Electromagnet, but I just can't remember what it is, and i can't find it any where.

of course the strength will depend on many things, # of coils, current, voltage?, Power? distance away from magnet and other things.
 
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  • #2
strenght of electromagnet will also depend on core.
 
  • #3
I am specifically looking for the formula I referred to earlier actually if anyone knows it.


While were talking about the core of the magnet,
how will the diameter of the (round) core effect the strength?
Lets give 2 extremes, a very small diameter, wouldn't that concentrate the magnetic field and make it very strong all the way through, as compared to a very wide diamter, which will only be semi-strong around the edges.
but if you "add" up the strength on both, would they be equal, it is just that on one it is more concentrated and another it is more spread out?
 
  • #4
Before getting a mathematical formula, you need to 'define' the strength of an electromagnet. If the definition is clear, the formula will follow immediately...
 
  • #5
mrjeffy321 said:
I think I remember there being a formula to determine the Strength of an Electromagnet, but I just can't remember what it is, and i can't find it any where.

of course the strength will depend on many things, # of coils, current, voltage?, Power? distance away from magnet and other things.
The field strength depends upon the current and the turn density as well as the permeability of the core. It does not depend on voltage, # of coils, or power. Sustaining a magnetic field does not require energy because no work is being done in maintaining the field. The power to a superconducting magnet should be very close to 0 but the magnetic field can be tremendous because of the current.

AM
 
  • #6
When I was referring to strength of a magnetic field , I am really referring to the force that it exerts on an objecft (like a metal plate for example), but I know this is wrong, that is the force of the field, I need to find the intensity/whatever you call it, which has a unit of Tesla
B=N/A*m
where B is the magnetic field, N is the force in Newtons the onject experiences, A is the amperage, and m is the length in meters if the wire that is experiencing the force.

although this isn't quite what I was looking for, it is a start.


Can you tell me what to look for specifically, so that I can narrow down my search and find the info I am looking for.
 
  • #7
mrjeffy321, I would be happy to solve this magnetostatic problem, involving a description of forces (Newtons) and fields (Teslas).

The field is highly dependent on the geometry so please describe precisely the geometry of the situation (or draw a paint picture. Also, the effect of the electromagnet on an external current (object) depends on the orientation of that current, so include that also.

Is it a solenoid (A long coil of wire wrapped around a ferromagnetic {iron} core)?
If it is, than I can tell you that the field H will go as:

[tex]H = \frac{\mu_0 I}{2\pi r} [/tex]

Where r is the perpendicular distance from the solenoid. H is not B, and is not F.

Then you need to know the magnetization of your material, which is difficult for ferromagnets, I will see if you have details.
 
  • #8
Well in my situation, I would have a solid Iron core, cyllendrical, wrapped with wires.
the object to be attracted would be something like a flat piece of sheet metal (to make it easy) so that they would rest against each other easily.

example picture, top object (minus the periods) is the magnet, the bottom is a flat piece of metal.

...| |
...| |
...| |
...| |
...|_|

...______________
 
  • #9
Then:

[tex] B = \mu I N [/tex]

where mu is the permeability of your metal, I is the current in the wire, and N is the number of turns per unit length ( valid if the object is near the core).
 
  • #10
so mu is a constant that I have to find for my partular material.
I found some constants dealing with this, but they are given diferently,
I found 3 different things, mu i/mu not, mu m/mu not, H c/A/m,
it says that mu i, is the initial permeability, mu m is the maximum permeabilty, and mu not is the magnetic permeabilty in free space.

is this number, say for Iron, generally very big, like 200 or 6000?

I is the current in amps.
N is the # of coils, (per unit length?)

is this "per unit length" part referring to how many coils I have per meter?
say I had a long (1 meter long) cyllendrical metal core, the N would be the number of coils I have total around the whole thing.
but let's say I had a 10 cm (.1 m) long core, so N would be equal to the number of coild I have * 10? or is this "unit" being referred to not the meter?

also, say I had a really wide (in diameter) core, would this matter any? as compared to a thin core?
 

What is an electromagnet?

An electromagnet is a type of magnet that is created by running an electric current through a coil of wire. This coil of wire then produces a magnetic field, which can attract or repel other magnets, or even magnetize materials that are normally not magnetic.

How is the strength of an electromagnet measured?

The strength of an electromagnet is typically measured in units called Gauss or Tesla. These units describe the density of the magnetic field at a given point. The stronger the magnetic field, the higher the Gauss or Tesla measurement will be.

What factors affect the strength of an electromagnet?

The strength of an electromagnet is affected by several factors, including the number of coils in the wire, the amount of current running through the wire, and the type of core material used. Increasing any of these factors will generally result in a stronger electromagnet.

How can the strength of an electromagnet be increased?

The strength of an electromagnet can be increased by increasing the number of coils in the wire, increasing the amount of current running through the wire, or using a stronger core material. Additionally, wrapping the wire around the core multiple times and using a thicker wire can also increase the strength of the electromagnet.

What are some practical applications of electromagnets?

Electromagnets have a wide range of practical applications, including electric motors, generators, MRI machines, and speakers. They are also used in industrial settings for lifting and moving heavy objects, and in everyday objects such as doorbells, credit cards, and computer hard drives.

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