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So i know that these following things will affect the strength of an electromagnet: Amperage going through the wire, the amount of coils of wire, and the ferromagnetic core. I also know the poles of an electromagnet are as follows: on the coil of wire the side that connects with positive is south pole, and the side that connects with negative is north pole. But can this happen, for example i take a long round piece of iron as my ferromagnetic core, and i loop some copper wire all the way to the end of the piece of iron, then i continue the loop from the start of the piece of iron to the end, and back again, and again. Will this affect the strength of the electromagnet positively or negatively as apposed to looping the wire thickly only one time but thickly?

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  • \$\begingroup\$ "... on the coil of wire the side that connects with positive is south pole ...". This is not correct. The direction of the magnetic field depends on the direction of the current around the axis - not along the axis. \$\endgroup\$ – Transistor Dec 23 '17 at 21:07
  • \$\begingroup\$ ^^^ This is known as Ampere's Law, not correcting you, @Transistor but just giving a follow up. \$\endgroup\$ – user103380 Dec 23 '17 at 21:12
  • \$\begingroup\$ @Transistor ok if there is AC current running in the wire, the felids will change. This is known. So then if i finish one full loop all the way across the ferromagnetic core, so iron, this will also have a posative and negative just not alternating. And then if we have a full loop, then another loop starting from the end right over to the beginning then to the end looping, will this change, weaken, or affect the already set north and south poles? \$\endgroup\$ – Ali Ragb Dec 23 '17 at 21:48
  • \$\begingroup\$ hyperphysics.phy-astr.gsu.edu/hbase/magnetic/amplaw.html#c1 \$\endgroup\$ – Bruce Abbott Dec 24 '17 at 0:53
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From the question comments:

"... on the coil of wire the side that connects with positive is south pole ...".

This is not correct. The direction of the magnetic field depends on the direction of the current around the axis - not along the axis.

So then if i finish one full loop all the way across the ferromagnetic core, so iron, this will also have a posative and negative just not alternating. And then if we have a full loop, then another loop starting from the end right over to the beginning then to the end looping, will this change, weaken, or affect the already set north and south poles?

A better way of saying it is, "So if I finish one full layer of the winding and then start a second layer at the end of the first and running back towards the start of the first ...". Provided you keep turning in the same direction around the axis you will be fine. That is how machine-wound coils are made.

enter image description here

See this YouTube video for an example.

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  • \$\begingroup\$ Wait a day or two to see if any better answers come in before accepting one (or mine). \$\endgroup\$ – Transistor Dec 23 '17 at 23:08

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