Electro and general magnet questions, need answers

[booth413]

1. is insulated wire ok to use on an electromagnet?
2. say you have an electro magnet in the form of a spool of wire with an iron core, would it be possible to wrap the entire assembly in a material that would contain the magnetic field produced by the current flow?
3. what is the strongest type of permanent magnet?
4. does overlapping layers of coiled wire strengthen an electro magnet?

[marcusl]

1. is insulated wire ok to use on an electromagnet?
2. say you have an electro magnet in the form of a spool of wire with an iron core, would it be possible to wrap the entire assembly in a material that would contain the magnetic field produced by the current flow?
3. what is the strongest type of permanent magnet?
4. does overlapping layers of coiled wire strengthen an electro magnet?
1. Yes, in fact it's a must. Enameled magnet wire is preferred to plastic insulation since you can pack the turns more tightly.
2. Yes, this is called a yoke. If you look at an AC transformer, you'll see that the winding is in the center with large return paths to either side kind of like this:
-----------
|| | | ||
|| coil ||
|| | | ||
-----------
This confines the magnetic flux lines and greatly increases efficiency.
In case of an electromagnet, the core would have a gap at the center for your application or experiment. Check out these big scientific electromagnets (the round cans contain the coils) for an example of this approach:
http://www.laboratorio.elettrofisico.com/eng/products.asp?famiglia=Electromagnetic%20Systems
3. Rare earth oxides. You can Wiki and google "rare earth magnets" and get a ton of hits.
4. Yes, absolutely. You'll find lots of information on designing them online. Write back with more specific questions.

[booth413]

ok thats a big help, heres some more specific questions.

1. what kind of material should i use to wrap the electromagnet?
2. where can i find enameled magnet wire?
3. whats the best way to switch the polarity of an electromagnet extremely quickly?