Help with electromagnet design

In summary, the conversation discusses building an electromagnet to pull a 5kg weight on a cushion of air. The speaker is trying to make the smallest electromagnet possible and asks for help with specifications for the design. There is confusion about using an iron core versus an air core and concerns about the battery's ability to handle the necessary current. It is also mentioned that the "cushion of air" is a metaphor and not actually involved in the design.
  • #1
unityunity
4
0
Hi everybody,

I just had 100m of copper winding wire arrive in the mail so I can build an electromagnet.

I'm aiming to pull a 5kg weight along, which is already floating on a separate magnetic field so all friction is removed except air resistance.

What I want to do is put an electomagnet in front of this 5kg box, to pull it along on a cushion of air - similar to the Japanese maglev trains.

(except mine is awesome).

So here's the thing.

I'm trying to make the smallest electromagnet I can out of this wire.

I wound it all around a little a plastic air core with a diameter of 6mm. There's 100 turns of wire, wire is 0.2mm, copper, 36SWG.

Hooked up a 9V battery.

Nothing - no force.

I know... you are going to say the number of turns is too low.

But before I spend the next 2 hours going mad winding up this tiny little thing with 100,000 turns, I wonder if someone could help me with a few specs for the design.

Best guess at what size radius core to use (air core), how many turns, and voltage to apply.

I'm stuck with standard battery voltages - multiples of 1.5v, or 9V.

Thanks for your help!
 
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  • #2
Use an iron core , Up the current .
 
  • #3
cragar said:
Use an iron core , Up the current .

Thanks for your reply.

I did try with an iron core - no effect.

I'm not sure how to up the current when the resistance is fixed (the length of wire) and the voltage is fixed within those ranges.
 
  • #4
You should be able to attract bits of iron with the magnet you have described, air core or iron core. Something is wrong. You did complete the circuit, right? One pole of the battery on one end of the wire, the other pole on the other end? Its possible that you are trying to draw too much current out of the battery, and are dropping its voltage when connected. You really need to be careful in this design. I think SWG36 will only handle about 70 milliamps of current, so you need to make sure that the resistance that your 9v battery sees is about 127 ohms. If the wire does not give you that, then you should drop your voltage until V=IR where I=0.07 amps (70 milliamps) and R is the resistance of your coil.
 
  • #5
unityunity said:
What I want to do is put an electomagnet in front of this 5kg box, to pull it along on a cushion of air - similar to the Japanese maglev trains.

It isn't on a cusion of air. Air has nothing to do with it.
I know... you are going to say the number of turns is too low.

Sounds like more than enough for a basic magnet.
I'm stuck with standard battery voltages - multiples of 1.5v, or 9V.

Put in an iron core and attach as many batteries as possible. If it doesn't attract, I'd say your batteries are cream-crackered.

However, you're not using AA, AAA and 9V (small rectangle) batteries are you? They can't deliver anywhere near enough current. 9V batteries are rated at around 0.2A. Connecting about 10 of them in parallel and you'll get enough to give a good field - although I wouldn't recommend this as it may be dangerous.
 
  • #6
jarednjames said:
It isn't on a cusion of air. Air has nothing to do with it.

It's a metaphor. As in poetry. Thankyou for pointing out the obvious.
 
  • #7
Thanks everyone. I got a tiny bit of pull from the electromagnet now.
 
  • #8
unityunity said:
It's a metaphor. As in poetry. Thankyou for pointing out the obvious.

Well it reads like a statement, and as such is wrong.
 

1. How do I determine the necessary specifications for an electromagnet design?

In order to determine the necessary specifications for an electromagnet design, you should consider factors such as the desired strength of the magnetic field, the size and shape of the magnet, the power source available, and any other specific requirements for your application. It may be helpful to consult with an experienced engineer or refer to design guidelines and standards.

2. What materials are commonly used for constructing electromagnets?

The most commonly used materials for constructing electromagnets are iron, steel, and various types of magnet wire. Iron and steel are used for the core of the magnet, while the magnet wire is wound around the core to create the magnetic field. Other materials, such as copper, aluminum, and various alloys, may also be used in some cases.

3. How can I calculate the magnetic field strength of an electromagnet?

The magnetic field strength of an electromagnet can be calculated using the formula B = (μ₀ * N * I) / L, where B is the magnetic field strength in teslas, μ₀ is the permeability of free space (a constant value), N is the number of turns in the coil, I is the current in amperes, and L is the length of the coil. It may also be helpful to use online calculators or software specifically designed for electromagnet design.

4. What are the safety considerations when working with electromagnets?

When working with electromagnets, it is important to consider the potential hazards associated with strong magnetic fields. These can include interference with electronic devices, attraction to ferromagnetic materials, and potential harm to individuals with pacemakers or other medical devices. It is also important to follow proper wiring and insulation techniques to prevent electric shocks.

5. How can I optimize the design of an electromagnet for my specific application?

To optimize the design of an electromagnet for a specific application, it is important to consider all of the relevant factors and requirements, such as the desired magnetic field strength, size and weight restrictions, and power source limitations. Experimentation and testing may also be necessary to fine-tune the design and achieve the desired results.

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