Calculation of magnetic force on a wire

In summary, the conversation discusses the possibility of moving a steel wire against frictional forces using a magnet. The approach for calculating the force acting on the wire is the same as any force calculation, or it can be measured directly. The dimensions of the wire and magnet are important factors, as well as the forces that need to be calculated. The conversation also mentions the complexity of computing the force and suggests starting with an idea of the range of magnetic strengths available. The type of steel and the geometry of the wire also play a role in its response to a magnet. The speaker suggests using the biggest magnet that can be easily carried, as it should be able to move a gram of steel wire through a few millimeters of PVC plastic.
  • #1
banerjeerupak
123
1
Hi,

I would like to know if it is possible to move a steel wire against frictional forces using a magnet. What would be the approach of calculating the force acting on that thin wire. I would know the dimensions of the wire and the dimensions of the magnet. What other values should I find from data table.

Thanks

Rupak
 
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  • #2
banerjeerupak said:
I would like to know if it is possible to move a steel wire against frictional forces using a magnet.
It is - you can easily see this with any handy magnet and a bit of wire since all normal situations involve friction to some extent.
What would be the approach of calculating the force acting on that thin wire.
Same as any force calculation - or you could measure it directly.
I would know the dimensions of the wire and the dimensions of the magnet. What other values should I find from data table.
Which forces do you need to calculate?
Take a look at the equations and definitions of the forces and see.
 
  • #3
You can definitely attract steel with a magnet, but the force is seriously complicated to compute. Don't hope for anything like B*I*L. It depends on how the wire's permeability deforms the field.
 
  • #4
... but it is the sort of thing sometimes offered as a homework problem in college e-mag courses. The geometry is usually simple and permeabilities are provided. I agree it's usually a pain. We really need the context to be of real help.
 
  • #5
What I am really trying to do is move a length of wire along a duct, from outside the duct. I will be doing it experimentally. However, it would help if I could calculate the strength of the magnet I would need rather than trying to guess and do it by trial and error.
 
  • #6
Start with an idea of the range of choice for magnetic strengths that will be available to you. If they only supply the one magnet, there's no point :)

Anyway - that will tell you how coarse-grained you need the calculation.

I take it the wire is expected to be lying lengthwise in the pipe?
How thick is the pipe and what is it made of?
How big and heavy is the wire?

Also see:
http://www.corrosionist.com/magnetic_response_stainless_steel.htm [Broken]
... I'm guessing the wire is not stainless steel, but the discussion will give you an idea of what you are asking. eg. different kinds of steel respond differently to a magnet.

I'd expect a basic classroom bar magnet to be able to move a gram or so of steel wire through a few mm of PVC plastic though. I'd just use the biggest magnet I can easily carry.
 
Last edited by a moderator:

1. How is the magnetic force on a wire calculated?

The magnetic force on a wire can be calculated using the formula F = ILBsinθ, where I is the current in the wire, L is the length of the wire, B is the magnetic field strength, and θ is the angle between the wire and the magnetic field.

2. What is the direction of the magnetic force on a wire?

The direction of the magnetic force on a wire can be determined using the right-hand rule. If you point your thumb in the direction of the current, and your fingers in the direction of the magnetic field, the direction that your palm is facing indicates the direction of the magnetic force.

3. How does the magnetic force change with the current in the wire?

The magnetic force on a wire is directly proportional to the current in the wire. This means that as the current increases, the magnetic force also increases. Similarly, as the current decreases, the magnetic force decreases.

4. Can the magnetic force on a wire be negative?

Yes, the magnetic force on a wire can be negative. This occurs when the current in the wire and the magnetic field are in opposite directions, resulting in a negative value for the force.

5. What factors affect the strength of the magnetic force on a wire?

The strength of the magnetic force on a wire is affected by the current in the wire, the length of the wire, the strength of the magnetic field, and the angle between the wire and the magnetic field. Additionally, the type of material the wire is made of can also affect the strength of the magnetic force.

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