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Re: There's work, and then there's work



At 17:58 -0800 1/29/03, David Rutherford wrote:

This is just about the response I figured you would give. When pinned
down and asked to answer specific, simple questions that would expose
your unwilligness to look at (or admit) what is actually being measured,
in the two experiments, you decline to answer them. You know that a particle
travelling parallel to the walls of the resistor will transfer _none_ of
its energy to the walls of the resistor, thus, it will cause no heating
of the water in the calorimeter and its kinetic energy will not be
accounted for in the calorimetric experiment. That means that the
kinetic energy due to the longitudinal components of the velocities of
all of the randomly moving particles is unaccounted for in the
calorimetric experiment. Since longitudinal motion is just as likely,
statistically, as transverse motion, _half_ of the kinetic energy of the
particles goes unaccounted for in the calorimetric experiment.

You also know that a particle travelling parallel to an imaginary
surface perpendicular to direction of the current does not pass through
that surface and is, therefore, not accounted for in the measurement of
the current. That means that its kinetic energy is not accounted for in
the current experiment. Therefore, the kinetic energy due to the
transverse components of the velocities of all of the randomly moving
particles is unaccounted for in the current experiment. Thus, for the
reason I gave above, _half_ of the kinetic energy of the particles,
also, goes unaccounted for in the current experiment.

You can't argue with anything I've said, here, and you know it, that's
why you didn't answer my questions. I used to have alot of respect and
admiration for physicists, but no more. I now know that you are not
interested in finding the truths of the universe; you are interested
only in perpetuating the status quo at any cost, even if it means
ignoring the truth. I only wish the rest of the world knew what a joke
you guys are.

I'm probably making a big mistake jumping in here, but this rant is
so over the top that it must be responded to even if the response is
ignored. It would appear, David, that you have not the least
understanding of the concept of energy. Energy, being a scalar
quantity does not have "components," although it is possible to
associate the energy that arises due to any given component of the
object's velocity. But the most important aspect of this is that the
path of an electron through a wire, or a resistor is not a straight
line but a more or less "biased random walk" involving lots of
bouncing around between the various atoms of the wire or resistor.
The current flows because there is a net electric field inside the
wire that is directed longitudinally. If the electrons didn't keep
hitting the atoms in the wire, they would speed up under the
influence of the electric field. But, once the current is established
and steady, they do not. Much like a block of wood sliding down an
incline at constant speed, they transfer what energy they might gain
as a result of the electric field, almost instantly to the lattice of
atoms that make up the wire or resistor, and this energy transfer
causes the atoms to oscillate a bit more than they were, which means
that they are now at a higher temperature. In a wire, there is less
energy transferred to the lattice than is the case in a resistor, so
it manages to claim more of the energy taken from the electric field
than does the wire. That's why it is called a resistor.

The energy that the electrons transfer to the resistor as they pass
through it can be shown to be exactly equal to the difference in
electrical potential between the ends of the resistor, multiplied by
the charge on the electron. This happens every time an electron bumps
into an atom, regardless of which way it is traveling at the time of
the collision. Because the atoms are "locked" in position in the
resistor, they can only vibrate, and that vibration is gradually
transferred to the surrounding liquid in the calorimeter experiment.
It is exactly the same energy that is found by measuring the current
in and voltage across the resistor as a function of time. Yes, the
only electrons that count in the current are those that pass the
surface across which the current is being measured. But that is all
the electrons that need to be counted, since if there were some not
crossing that boundary, they would pile up in one point and lead to
an excess of charge at that point. Which is *never* observed.

Furthermore, the electrons are *not* equally as likely to be
traveling in transverse direction as they are in longitudinal
directions. Since there is an electric field in the wire, the
electrons will spend a bit more time moving along the resistor than
across it. This is the "bias" I mentioned above. You seem to be
assuming that the resistor is like a pipe, with all the electrons
flowing nicely down the pipe without any impediment, and that's not
the way it is. Individual electrons are continually changing
directions, every time they hit an atom. And every time they hit an
atom they give up a bit of their energy and the atom gains it. If the
current is large, the electrons are giving up more energy tot he
atoms than the atoms can dump to their surroundings, so the resistor
heats up (i.e., the atoms locked in it have more individual
vibrational energy). It is this excess thermal energy that the
resistor picks up from the electrons that appears as increased
temperature in the water of the calorimeter, eventually. There is no
distinction between longitudinal electrons and transverse electrons.
They are all at one time or another moving in all directions, and
there is no concern about missing any current, since for every
electron that enters the resistor, one leaves the other end. so the
current meter counts all the current. None is lost. The electrons
that come out of the far end of the resistor will have the same
kinetic energy that they had when they entered (except for a very
tiny increase that would be due to the increasing temperature of the
resistor, but that is negligibly small compared to the kinetic energy
of the electrons when they enter the resistor. Therefore, we can
reliably say that all of the energy they would have gained as a
result of the electric field, had they been able to move without
impediment through the resistor, has instead been transferred to the
resistor, and shows up there as an increase in temperature.

Yes we can argue with everything you have said. I suspect no one has
bothered to explain things at this basic level because we have all
assumed that you understood that. It is clear to me now that you
don't. Please read a good elementary textbook and find out how
currents in wires really work. Then you will find out where you have
been making your errors. The person who is not listening here is you.
We have been very patient with you, trying to explain where we think
you might have gone wrong, when we understood your questions, but all
too often your questions or statements were so strangely worded that
we could not understand what your points were.

Remember, no science can be trusted unless it is soundly backed by
observations. You have provided no observations to support your
claims and have not listened to the responses to your mostly
outrageous statements. If you want to participate in this list, we
are willing to help you to understand, to refer you to sources where
your misconceptions can be corrected, and answer rational questions,
and even debate you when the questions are one of substance--we do
that all the time amongst ourselves, sometimes even with a bit of
rancor. But our patience runs thin when a correspondent persists in
making claims that have been adequately dealt with within the current
theories, and are repeatedly verified by high school students every
day. While we are jolly fellows, I fear that the appellation "joke"
resides with you.

It is time you learn whereof you speak, or stop talking. There are
plenty of places you can go to get a basic introduction to physics
(try your local community college). This list is intended for physics
teachers to discuss aspects about physics and physics pedagogy among
those who have a basic understanding of the subject. When you can
bring that to the list, we will welcome your input.

Hugh
--

Hugh Haskell
<mailto:haskell@ncssm.edu>
<mailto:hhaskell@mindspring.com>

(919) 467-7610

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