I've been looking at this description of the Faraday paradox:
http://en.wikipedia.org/wiki/Faraday_paradox#Inapplicability_of_Faraday.27s_law
The description doesn't make sense to me in terms of telling me what is
going
on here. The wording does not seem to be complete. What is unclear here
is
exactly what is moving. It only talks about the strip being conducting at
a
fixed location. So where is the movement? Or is there any?
I see two ways to interpret the wording (which would, of course, impact
the
science being described).
1. A strip of semi-conducting material is physically moving, but the
****tion
that is capable of conducting is held stationary by a stationary light
beam that controls that conductivity.
2. A strip of semi-conducting material is stationary, but the ****tion
that is
capable of conducting is moving as directed by the moving light beam
that
controls that conductivity.
Maybe it might be clearer, at least for what I want to learn initially
from
this, to describe it in different terms.
My understanding of the homopolar generator is that the entire disk would
be
under the influence of a uniform magnetic field that, from the point of
any
particle of the rotating disk, is not changing in intensity (so as to not
be
influenced by Faraday's law of induction which would apply when the field
is
changing). The paradox is that when the disk is rotating, it does not
matter
if the magnet(s) creating the field are rotating with the disk or not (or
in
any other way including in the opposite direction).
Maybe this experiment would be more telling?
Suppose we have 2 electrically conductive rails with a substantial ****tion
of
them placed in a uniform magnetic field. The field direction cross at
right
angle to the shortest distance between the rails. For convenience I would
lay the 2 rails along a table that has a very slight tilt. Long magnets
would
be placed above and below the position of the rails. At the high end of
the
rails I attach a voltmeter to the 2 rails. Then I place a round copper
bar
on the rails (with grooves to keep it from turning and sliding off). I
let
the copper bar roll down the rails to the ****tion of the rails in the
magnetic
field. Maybe the bar should slide instead of roll to simplify how the
Lorentz
force would work here. When the bar is moving within the magnetic field,
it
gets an electric charge which is carried back on the rails to the
voltmeter.
The voltmeter should show the generated voltage if this setup is correct.
Motion (of the bar) is in the direction the rails "run". Electric
potential
and thus current in the bar is between the 2 rails. The magnetic field is
right angle to the motion and electric current.
Unlike the disk experiment which can run continuously, the bar will
eventually
run out of the area of magnetic field, and of the rails.
Next question: If the magnets are smaller and move along with the bar,
this
should still produce the same electric potential, right? This should be
the
equivalent, in the disk experiment, of the magnet rotating with the disk?
What I am interested in determining is if this method of generating
electricity
really does not specificaly require rotation, and that rotation is merely
a
convenient construction so that the motion can continue for a long time.
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to
ignorance |
| by the abuse department, bellsouth.net is blocked. If you post
to |
| Usenet from these places, find another Usenet provider ASAP.
|
| Phil Howard KA9WGN (email for humans: first name in lower case at
ipal.net) |
|
