Re: Basic Question

In sci.physics.electromag, jimp@xxxxxxxxxxxxxxxxxxxx wrote:
EskWIRED@xxxxxxxxxxxxxxxxxxx wrote:
In sci.physics.electromag, jimp@xxxxxxxxxxxxxxxxxxxx wrote:
EskWIRED@xxxxxxxxxxxxxxxxxxx wrote:

Ummm....using any wire of any thickness and a given resistance per unit of
length, why is it that more voltage will yield more current? Is it a
matter of velocity of electron flow?

Because E=IR which is basic Ohm's Law.

That I know. The question is why.

You mean why does Ohm's Law work?

Pretty much.

Ohm's law is an abstraction of physical phenomenon. We measure various
aspects of electricity, and create a tautology by saying that if you
multiply two of them, the third is defined as the product. It works
perfectly. You can manipulate these measurements any way you like, and
you will always end up with the answer being correct. If you have any two
of them, the third is trivially easy to deduce.

But what I am asking about is not manipulation of abstractions. I am
asking about what is happening on a physical level.


It was a homework problem and extended classroom discussion when I went to
school. Feel free to have the experience.

You can't get there without math.

I cannot discover how the same amount of power can go through a thinner
wire if the voltage is increased? Bullshit. At some point, the
phenomenon was discovered, and the explanation led to the math. It was
not the other way around.

All the math does is to make it easy to get a correct answer, whether
you understand the undelying phenomenon or not.




The magnetic field propogates at c.

I thought that electromagnetic fields propogated at C only in free space.
Doesn't a wire provide significant resistance?

Yes, but resistance has nothing to do with the velocity of propagation,
that is determined by the dielectric constant.

Interesting.


The velocity of propagation or velocity factor is a parameter that
characterizes the speed of an electomagnetic wave through a medium.

The VOP of free space is 1.

The VOP of a medium is the reciprocal of the square root of the dielectric
constant of the medium.

See? This is the problem I always have with mathematical descriptions of
physical phenomenon.

The VOP depends entirely on the physical properties of the medium. We take
that physical property, run it through a mathematical function, and define
the answer to be the diaelectric constant of the medium.

But when described mathematically, we go backwards. We take the
abstraction, the answer to an arithmetic problem, the dielectric constant,
and say that the VOP depends upon it.

It is true that one can calculate VOP using this method. But this method
does nothing to explain what the heck is going on in the real world.




For a bare wire in air the VOP is about 0.99 as the dielectic constant
of air is about 1.0005.

For a wire covered with solid polyethylene the VOP is about 0.66 as
the dielectric constant of polyethylene is about 2.25.

Fascinating. In both cases, the copper is the same. The area AROUND the
copper determines the VOP of the circuit.

Why is that? What the heck is going on?



Are you saying that low voltage electricity travels at the same velocity
as high voltage electicity?

Yes, the velocity of propagation depends only on the dielectric constant
of the propagation medium.

And what determines the dielectric constant of the propogation medium? I
take it that this is not a mystery.


--
The whole problem with the world is that fools and fanatics are always so
certain of themselves, but wiser people so full of doubts.
-- Bertrand Russel

.

Relevant Pages

  • Re: Basic Question
    ... why is it that more voltage will yield more current? ... matter of velocity of electron flow? ... that is determined by the dielectric constant. ... characterizes the speed of an electomagnetic wave through a medium. ...
    (sci.physics.electromag)
  • Re: Basic Question
    ... matter of velocity of electron flow? ... characterizes the speed of an electomagnetic wave through a medium. ... the dielectric constant of polyethylene is about 2.25. ...
    (sci.physics.electromag)
  • Re: Basic Question
    ... matter of velocity of electron flow? ... characterizes the speed of an electomagnetic wave through a medium. ... the dielectric constant of polyethylene is about 2.25. ... the velocity of propagation depends only on the dielectric ...
    (sci.physics.electromag)
  • Re: Basic Question
    ... matter of velocity of electron flow? ... characterizes the speed of an electomagnetic wave through a medium. ... the dielectric constant of polyethylene is about 2.25. ...
    (sci.physics.electromag)
  • Re: more ignorant questions, no offense intended at all - just very curious
    ... That's not much different from the modern physics definition, which is basically that vacuum is what's left when you remove everything that can be removed. ... The ground state of hydrogen is simply an electron superimposed on a proton -- it only has a nonzero size because of the uncertainty principle. ... as far as I know the hard part isn't making fusion happen, it's getting out more energy than you put in. ... light in the medium of he matter of which our bodies is composed? ...
    (sci.physics)