Re: Basic Question

On Sep 5, 10:15=A0am, j...@[EMAIL PROTECTED]
 wrote:
> EskWI...@[EMAIL PROTECTED]
 wrote:
> > In sci.physics.electromag, j...@[EMAIL PROTECTED]
 wrote:
> >> EskWI...@[EMAIL PROTECTED]
 wrote:
>
> >> > Ummm....using any wire of any thickness and a given resistance per
u=
nit of
> >> > length, why is it that more voltage will yield more current? Is it
a
> >> > matter of velocity of electron flow? =A0
>
> >> Because E=3DIR which is basic Ohm's Law.
>
> > That I know. =A0The question is why. =A0
>
> You mean why does Ohm's Law work?
>
> The simple answer is you start with Maxwell and work your way into Ohm.
>
> It was a homework problem and extended classroom discussion when I went
t=
o
> school. Feel free to have the experience.
>
> You can't get there without math.
>
> >> The magnetic field propogates at c.
>
> > I thought that electromagnetic fields propogated at C only in free
spac=
e. =A0
> > 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.
>
> 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
dielectri=
c
> constant of the medium.
>
> 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.
>
> > Are you saying that low voltage electricity travels at the same
velocit=
y
> > as high voltage electicity?
>
> Yes, the velocity of propagation depends only on the dielectric constant
> of the propagation medium.
>
> --
> Jim Pennino
>
> Remove .spam.sux to reply.

dielectric constant can vary due to tempature and pressure as well