Questions about equivalents of audio/video and digital/analog.

Floyd L. Davidson wrote:
"David J Taylor"
wrote:
Floyd L. Davidson wrote:
[]
Yes, the electrical fields can take any value. It is
inherently an analog medium. But that has no
relationship to the signal which is used to send a
message.

May not be true when you consider quantum effects.....

Then again, it might still be true, even considering
quantum effects...

Electrons don't necessarily all just line up in a row
and proceed to flow along a conductor, all at the same
speed and all in the same direction.

Instead each one takes its own path, at its own speed,
and at any given time is going in its own direction.
(As with humans, there is an average... but no individual
actually is average.) We don't actually see the effects
of individual electrons, we see the effects of massive
numbers of electrons.

Electic current is not a quantum mechanism that happens
in discrete increments per electron, even though we
measure it in electrons passing a point. It is analog.

I think that electric currents (or at least the charge) must be quantised,
although not, as you say, on the macro scale we normally observe. At very
low rates, for example, you either get 4 electrons in a second or 5.
There's no halfway house. Averaged over ten seconds, the same flow might,
of course, be 44, 45, 46 or 47 electrons etc. So it will have a mean
value plus some (what I might term) quantisation noise. Perhaps even
Poisson noise.

David

"David J Taylor" wrote:
Floyd L. Davidson wrote:
"David J Taylor"
wrote:
Floyd L. Davidson wrote:
[]
Yes, the electrical fields can take any value. It is
inherently an analog medium. But that has no
relationship to the signal which is used to send a
message.

May not be true when you consider quantum effects.....

Then again, it might still be true, even considering
quantum effects...

Electrons don't necessarily all just line up in a row
and proceed to flow along a conductor, all at the same
speed and all in the same direction.

Instead each one takes its own path, at its own speed,
and at any given time is going in its own direction.
(As with humans, there is an average... but no individual
actually is average.) We don't actually see the effects
of individual electrons, we see the effects of massive
numbers of electrons.

Electic current is not a quantum mechanism that happens
in discrete increments per electron, even though we
measure it in electrons passing a point. It is analog.

I think that electric currents (or at least the charge) must be quantised,
although not, as you say, on the macro scale we normally observe. At very
low rates, for example, you either get 4 electrons in a second or 5.

I don't think so. You get one electron whizzing back
and forth 4000 times in that second, and another doing
it 3000 times, while a third is doing it 5 million
times. And another one goes past your point of measure
exactly 1 time only, and never comes back. And every 5
times an electron goes by and never comes back, another
one just plain goes backwards across your line and never
comes back.

Current is not how many went by, its the sum of how many
went in each direction, and how many times they did it.

There's no halfway house. Averaged over ten seconds, the same flow might,
of course, be 44, 45, 46 or 47 electrons etc. So it will have a mean
value plus some (what I might term) quantisation noise. Perhaps even
Poisson noise.

They aren't anything like that stable! We can't come up with
1 electron of current, or even dozens.

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

Floyd L. Davidson wrote:
[]
I don't think so. You get one electron whizzing back
and forth 4000 times in that second, and another doing
it 3000 times, while a third is doing it 5 million
times. And another one goes past your point of measure
exactly 1 time only, and never comes back. And every 5
times an electron goes by and never comes back, another
one just plain goes backwards across your line and never
comes back.

Current is not how many went by, its the sum of how many
went in each direction, and how many times they did it.

There's no halfway house. Averaged over ten seconds, the same flow
might, of course, be 44, 45, 46 or 47 electrons etc. So it will
have a mean value plus some (what I might term) quantisation noise.
Perhaps even Poisson noise.

They aren't anything like that stable! We can't come up with
1 electron of current, or even dozens.

I must confess - I was thinking of DC rather than AC.

Charge is the measure of what goes by, and current is the rate of flow of
charge. I haven't worked out what 10 or 100 electrons per second
corresponds to, but I guess you would see quantum effects at that small
current flow.

Google tells me e = 1.60217646 × 10^-19 coulombs, so 100 of those per
second is about 16 x 10^-18, or 16 attoamps....

David

"David J Taylor" wrote:
Floyd L. Davidson wrote:
[]
I don't think so. You get one electron whizzing back
and forth 4000 times in that second, and another doing
it 3000 times, while a third is doing it 5 million
times. And another one goes past your point of measure
exactly 1 time only, and never comes back. And every 5
times an electron goes by and never comes back, another
one just plain goes backwards across your line and never
comes back.

Current is not how many went by, its the sum of how many
went in each direction, and how many times they did it.

There's no halfway house. Averaged over ten seconds, the same flow
might, of course, be 44, 45, 46 or 47 electrons etc. So it will
have a mean value plus some (what I might term) quantisation noise.
Perhaps even Poisson noise.

They aren't anything like that stable! We can't come up with
1 electron of current, or even dozens.

I must confess - I was thinking of DC rather than AC.

No, that *is* DC!

Electrons just are not all that well mannered. It isn't
quite like herding cats, but there are similarities.

Charge is the measure of what goes by, and current is the rate of flow of
charge. I haven't worked out what 10 or 100 electrons per second
corresponds to, but I guess you would see quantum effects at that small
current flow.

I doubt it.

Google tells me e = 1.60217646 × 10^-19 coulombs, so 100 of those per
second is about 16 x 10^-18, or 16 attoamps....

Probably not enough current to shock anyone... :-)

--
Floyd L. Davidson http://www.apaflo.com/floyd_davidson
Ukpeagvik (Barrow, Alaska)

Floyd L. Davidson wrote:
"David J Taylor"
wrote:
Floyd L. Davidson wrote:
[]
I don't think so. You get one electron whizzing back
and forth 4000 times in that second, and another doing
it 3000 times, while a third is doing it 5 million
times. And another one goes past your point of measure
exactly 1 time only, and never comes back. And every 5
times an electron goes by and never comes back, another
one just plain goes backwards across your line and never
comes back.

Current is not how many went by, its the sum of how many
went in each direction, and how many times they did it.

There's no halfway house. Averaged over ten seconds, the same flow
might, of course, be 44, 45, 46 or 47 electrons etc. So it will
have a mean value plus some (what I might term) quantisation
noise. Perhaps even Poisson noise.

They aren't anything like that stable! We can't come up with
1 electron of current, or even dozens.

I must confess - I was thinking of DC rather than AC.

No, that *is* DC!

Electrons just are not all that well mannered. It isn't
quite like herding cats, but there are similarities.

Charge is the measure of what goes by, and current is the rate of
flow of charge. I haven't worked out what 10 or 100 electrons per
second corresponds to, but I guess you would see quantum effects at
that small current flow.

I doubt it.

Google tells me e = 1.60217646 × 10^-19 coulombs, so 100 of those per
second is about 16 x 10^-18, or 16 attoamps....

Probably not enough current to shock anyone... :-)

Thanks, Floyd - I'll have to leave it for the moment....

CHeers,
David