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Re: Charge of Electricity, vs. "electric charge"



During an electric current in a wire, it is the silvery
"electricity" which flows. I admit that this doesn't work for
electrolytes and plasmas.

Doesn't? Not exactly. The electrolytes I'm familiar with have too low a
conductivity to have broad vis. wavelength reflectivity. (prob. reflect fine at
long wavelengths, e.g. microwave). I haven't seen it, but I suspect molten salt
is "silvery" Dense plasmas reflect fine, hard to detect tho, as are emitting
light.

The double pulse signature of a nuclear fireball is an example of the reflection
(and absorption) of a plasma.

bc

William Beaty wrote:

On Sat, 20 Apr 2002, John Clement wrote:

The point of view of teaching the subject should actually be different from
the view that a professional physicist has. While it is convenient to
specify charge as a continuous property, this point of view produces
confusion for the beginning student. Anton Lawson in a remarkable series of
papers in Jour. of Res. in Sci. Teach. (JRST) has shown that concepts which
involve "invisible" things are much more difficult for students to
understand.

This is a much stronger argument against using "charge." I see analogy
with the early introduction of the infamous solar-system model for an
atom, and only later replacing it with the modern concepts. It lets kids
get conceptual hooks into atoms and chemistry, yet it doesn't seem to
create enormous misconceptions.

On the other hand, we could turn this problem on its head by noting the
historical development of the "charge" concept. Researchers of old had no
trouble in dealing with electric charge. They *knew* it was a substance
called "Electricity."

1700 - Electricity is a substance: Vitreous and Resinous electricity

1800 - Electricity is a substance: Negative and Positive electricity,
and electricity can flow through conductors as electric current.

1900 - Electricity is a substance, but quantities of electricity are
found to be quantized.

1910 - Electricity is a component of matter (of atoms) and sub-atomic
particles either carry quantities of electricity, or they
behave like "atoms" made of pure electricity.

1930 - Subatomic particles have many features, and some also carry
a charge of electricity along with them.

1960 - Elementary particles have the abstract property called "charge"

These dates are only approximate. Note well the sudden change around 1930
- 1960: suddenly "charge of electricity" has become "electric charge."
Electrons aren't particles of electricity anymore. They don't carry
electricity, instead they just have a property called "charge." And we no
longer speak of the flows of electricity inside of wires. In other words,
the theory of Electric Fluid has stolen away into the night. And nobody
noticed.

As for beginners, I don't think it's hard for them to imagine an invisible
substance called "electricity" which can flow through wires. We can even
use some modern research, and point out that the stuff within wires is
certainly not invisible. In metals, the electron-sea itself is silvery
(metallic- looking), therefore electricity within wires is a silvery
substance. During an electric current in a wire, it is the silvery
"electricity" which flows. I admit that this doesn't work for
electrolytes and plasmas.

The opposite stance is somewhat absurd. If electricity is not a substance
but instead is JUST an abstract property, then a flow of charge would be
as silly as a flow of "blueness". As a result, we must stop talking as if
charge was a substance, and we must stop saying that electric current is a
flow of "charge". Electric current is just an abstract property itself;
it's caused by the relative motion of another abstract property. We
should go back to calling it by the name "electric intensity" rather than
"electric current." Light bulb filaments get hot because the electric
Intensity within the metal is high, not because there are tiny particles
of Electricity flowing through the metal.

In my opinion, if we insist that "electric charge" is JUST an abstract
property, while we reject the concept "charge of electricity", then we
remove an extremely useful tool from students' mental toolkit. We take a
piece of everyday reality and we turn it into an abstract concept. Before
doing so, I think we should carefully examine our reasons for this.

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