when creating a large electromagnet, can you overlap the insulated wires on top of each other?

Question

using the same wire that is used for wiring up a house for elctricity, what is the best way to rig it up so I can plug it into the outlet without blowing the circuit breaker? AND if I am using a three foot iron rod, how do I tell which end is which polarity? and are there instruments for measuring guass?

and why use insulated wires?

can I use non-insulated wires

and what gauge wire should I use?

and how to I measure the gauss?

and when using a compass to check which end is which polarity - which polarity will the compass be attracted to?

and if I am using a three foot long core what kind of metal should that be made out of? Iron? steel? etc?

And if I want to get the maximum effect? how thick should that core be? 2 inches?

I plan on rigging it so I can plug it into the wall outlet.

Answer 1

Q: when creating a large electromagnet, can you overlap the insulated wires on top of each other?

A: Yes, if they are insulated, then you can overlap them. But bear in mind that the strength of an electromagnet greatly depends on amount of current, and number of windings of the wires. Thicker wires (small AWG) have less resistance thus can carry more current, but end up taking more space (less winding).


Q: using the same wire that is used for wiring up a house for electricity, what is the best way to rig it up so I can plug it into the outlet without blowing the circuit breaker?

A: The house wiring wires have thick rubber insulation, you will end up a winding with really big diameter. The problem with that is, the wire on the outer layers of the winding will be located too far from your rod, therefore cannot effectively induce electromagnetism on the rod. Your best bet is to use medium thickness magnet wire (aka enameled copper wire), as you may need up to 5000 winding on your rod or more (that's just a rough estimate).

Another point is, the wall outlet produce AC current. AC current will cause your magnet polarity (north and south) to continuously flip. You best bet is to first convert it to DC using an AC-DC adapter, then connect it to your electromagnet setup. That way you will have a fixed north and south on your magnet. Check your local electrical store for AC-DC converter/adapter. A car battery is also a good alternative.


Q: AND if I am using a three foot iron rod, how do I tell which end is which polarity.

A: Polarity is determined by the right-hand-rule. An example, if you hold an iron screw with it's head facing you, and the current (from positive to negative) that is flowing in the wire winding is counter-clock-wise, then the screw head will be the North. If the current flowing in the winding is clock-wise, the screw head is South. Polarity is determined by the direction of current flow, not the direction of wire winding.
To simplify matters, simply use a compass, or a another magnet that have it's North and South marked.


Q: and are there instruments for measuring guass?

A: There are Gaussmeter that uses hall effect, Fluxmeter, and Teslameter that you can use to measure the strength of your electromagnet.

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Answer to your edited questions:

Q: and why use insulated wires? can I use non-insulated wires?
A: If you wind using uninsulated wire, the circuit will be shorted. Current won't flow around (circling) the rod, instead it will take shortest path, which is on the surface of the wire that came in contact with each other in the winding. The rod will nonetheless be magnetized, but it will be VERY weak, almost negligible. Refer to my previous answer for info on current.


Q: and what gauge wire should I use?
A: Greatly depends on how much current you are planning to use. A good rule of thumb, if the wire heats up when current pass through it, then you need to use thicker wire. My guesstimate for your case is 0.5-1.5mm thick wire (that’s between 24 to 14 AWG). And use enameled copper wire, a copper wire insulated with very thin layer of enamel.


Q: and how to I measure the gauss?
A: refer to my other answer.

Q: and when using a compass to check which end is which polarity - which polarity will the compass be attracted to?
A: The North of the compass will be attracted to the South of the electromagnet, and vice versa.

Q: and if I am using a three foot long core what kind of metal should that be made out of? Iron? steel? etc?
A: Get the most permeable metal you can find. High permeability of the metal will make your electromagnet stronger. The best is to use Mu-Metal (75% nickel, 15% iron, plus copper & molybdenum), it has the highest permeability at 25000N/A2. Steel has permeability of 857N/A2, and iron (depending on the grade) have around 2000N/A2 - 5000N/A2.
Find the same grade of iron being used in electric transformer, and you'll be fine. If not, any iron rod will do.


Q: And if I want to get the maximum effect? how thick should that core be? 2 inches?
A: Maximum effect to do what? To get maximum strength, get maximum number of windings, and maximum current. The use of the iron core is just to "focus" the electromagnetic field created by the coil wire. 2 inch thick rod will mean the electromagnetic flux will be densely focused through a 2inch diameter surface, and 20inch thick rod means the flux will will be spreaded through 20inch diameter surface. The magnitude of the magnetic flux remains the same, only the density is different.
Btw, if your rod is 2inch thick, you will need at least 2500+ feet of wire to get 5000 windings, that sure will hurt the pocket a bit.

Q: I plan on rigging it so I can plug it into the wall outlet.
A: Use a high current AC-DC adapter/converter, plug it into your wall.

Answer 2

Creating An Electromagnet

Answer 3

You can overlap coils of insulated wire to increase the strength of the magnetic field. It is not as efficient as using thinner wire to pack coils together more closely, but it will still work, and won't have the high resistance of thin wire.

Answer 4

Regarding overlap:

http://www.viewimages.com/Search.aspx?mid=3326102

Regarding insulation: if you don't know why you should use insulated wire, stay away from the wall outlet. Use batteries instead - you're less likely to kill yourself.