winding an electromagnet on a nail

When I was a kid, I wound a nail with enamel-coated wire, starting from the head of the nail, then when I reached the tip, I would wind towards the head again (still in the same direction of rotation though).

Was this a mistake?

Would I have had a stronger electromagnet if I had a straight run of wire back to the head of the nail, then proceeded with winding?

 

[Kaz Kylheku]

On 2014-02-13, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:

Would I have had a stronger electromagnet if I had a straight run
of wire back to the head of the nail, then proceeded with
winding?

In short, no.

--
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ADA MP-1 Mailing List: http://www.kylheku.com/mp1

 

On Thursday, February 13, 2014 5:12:28 AM UTC-8, Jasen Betts wrote:

On 2014-02-13, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:

When I was a kid, I wound a nail with enamel-coated wire, starting from the head of the nail, then when I reached the tip, I would wind towards the head again (still in the same direction of rotation though).



Was this a mistake?



Would I have had a stronger electromagnet if I had a straight run of wire back to the head of the nail, then proceeded with winding?



It's the direction of rotation that matters, going straight back to

the top and doing a second layer waould have wasted wire, and also

made the turns looser, two bad things.

Ok thanks guys!

Michael

 

[Jasen Betts]

On 2014-02-13, mrdarrett@gmail.com <mrdarrett@gmail.com> wrote:

When I was a kid, I wound a nail with enamel-coated wire, starting from the head of the nail, then when I reached the tip, I would wind towards the head again (still in the same direction of rotation though).

Was this a mistake?

Would I have had a stronger electromagnet if I had a straight run of wire back to the head of the nail, then proceeded with winding?

It's the direction of rotation that matters, going straight back to
the top and doing a second layer waould have wasted wire, and also
made the turns looser, two bad things.

--
Neither the pheasant plucker, nor the pheasant plucker's son.


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[Tim Wescott]

On Thu, 13 Feb 2014 01:26:18 -0800, mrdarrett wrote:

When I was a kid, I wound a nail with enamel-coated wire, starting from
the head of the nail, then when I reached the tip, I would wind towards
the head again (still in the same direction of rotation though).

Was this a mistake?

Would I have had a stronger electromagnet if I had a straight run of
wire back to the head of the nail, then proceeded with winding?

No. It's the number of turns all going in the same direction that make
it work.

As a thought experiment, consider replacing 100 turns of enameled wire
with 100 turns of really thin insulated foil -- your electromagnet would
behave pretty much the same at DC, although I wouldn't answer for any
inter-winding capacitance issues.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com