Date: Wed Mar 18 08:58:51 2009 ** **Back to Contents ** ------------------------------------------------------------------------ **

Author: chuck...

Subject: Re: Power Lines and compasses?

Post:

depends upon how large a diameter loop you use and the number of turns ()
in the secondary, especially under the wires. Would you like 'fried' with

cheers,
chuck...

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu [mailto:tap-l-owner@lists.ncsu.edu] On
Behalf Of Richard Heckathorn
Sent: Tuesday, March 17, 2009 9:57 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Power Lines and compasses?

Greetings,

Have any of you connected a long extension cord to a voltmeter and then
swung it as a jump rope out in the open, no overhead wires? At what
orientation does one get an induced voltage? That I leave up to you to
experiment to find the answer if you do not know.

Now having never tried it, is there any difference if I swing it under a
high tension wire?

Dick

Helping teachers who facilitate, motivating students who learn.
Dick Heckathorn 14665 Pawnee Trail Middleburg Hts, OH 44130 440-826-0834
http://web.cvcaroyals.org/~rheckathorn/
Adjunct Physics Teacher - Baldwin Wallace College Physics is learning how to
communicate with ones environment so that it will talk back.

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu
[mailto:tap-l-owner@lists.ncsu.edu] On Behalf Of
Sam Sampere
Sent: Tuesday, March 17, 2009 12:43 PM
To: 'tap-l@lists.ncsu.edu'
Subject: Re: [tap-l] Power Lines and compasses?

I have a demo where you plug a coil into 120 VAC,
and a 100 W lamp in series with another coil
lights up when the coils are brought near. I had
a graduate student tell me that ALL my compasses
were defective. None showed a deflection when
brought near the coil. Silly grad student.

I wound a large multiturn coil around the
projection screen in the auditorium. An amplifier
driven by a function generator supplies 10+ amps
through this coil. It's fun to watch the large
demo compass turn slowly, i.e. 1 Hz.

Sam

-----Original Message-----
From: tap-l-owner@lists.ncsu.edu
[mailto:tap-l-owner@lists.ncsu.edu] On Behalf Of
Zani, Gerald
Sent: Tuesday, March 17, 2009 11:23 AM
To: tap-l@lists.ncsu.edu
Subject: Re: [tap-l] Power Lines and compasses?

I laid a hall probe onto an AC power cable
attached to a 90 Watt lamp
and measured the B field. Nothing.

Then I wound the AC power cable into a few loops
and measured with the
hall probe. Nothing.

Then I placed a compass on the same AC power cable
for with a 90 Watt
lamp and looked for a deflection.

Nothing.

The article neglected to assume it was spherical
cow...

- JZ

"To do nothing at all is the most difficult thing
in the world, the most
difficult and the most intellectual." -- Oscar
Wilde

On 3/17/09 6:42 AM, "cbettis@unlserve.unl.edu"

wrote:

> I just read an article in the newspaper this
morning claiming that
> power lines affect cattle's sense of direction.
The researchers say
> that generally cattle tend to line themselves up
with the earth's
> magnetic field (which, along with our magnetic
declination, may
> explain cow dipping in our neck of the woods ;-)
but if they are near
> power lines they don't. My puzzlement is that
the average magnetic
> field from a power line ought to be zero since
they transmit AC power
> and they are strung in pairs. So I was wondering
if any of you have
> experience with using compasses around power
lines (or around cattle
> for that matter;).
>
> Cliff
>

From tap-l-owner@lists.ncsu.edu Wed Mar 18 08:58:51 2009
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