[Amps] "Conventional" current flow

[K9FFK]

OK, Jim!

Good explanation. I can agree with that speed. I should have been more 
precise. My point was that the electrons were moving very fast and 
drifting about as in a wire and the electrons are carrying their charge 
to the anode. The charge does not zip ahead of the physical electron, as 
in a wire.

One million meters/second, finite transit time, upper frequency limit.

Life is good.

73, Dick K9FFK


On 12/2/2016 6:53 PM, Jim Garland wrote:
> Ahh, we're back on this thread! It's an interesting discussion. Dick's
> comments, below, are mostly correct about electrons traveling from a heated
> cathode to the anode. However, electrons don't move anywhere near the speed
> of light. They start off with thermal kinetic energy from the hot cathode,
> probably a few hundred meters per second, and then pick up speed as they're
> sucked toward the anode by the plate-cathode potential voltage. Typically
> they crash into the plate (depending on the plate voltage) with a speed of
> about a million meters per second, which is roughly one percent the speed of
> light, which is still pretty fast, and certainly much faster than the
> so-called "drift velocity" of the electrons in a copper wire. That's about 1
> cm per second, so you can think of the electrons in a metal moving like warm
> sludge, just oozing along the length of the wire. That fact alone suggests
> that the relationship between electric current and moving charges is more
> complicated than one might imagine. For example if you measure a fast pulse,
> say 1 nsec duration, on a coax cable, then obviously there's more going on
> than slowly moving charges migrating like sludge down the cable.
>
> Now, at the risk of muddying the water further, the picture of electrons as
> tiny little particles carrying an electric charge dates from early twentieth
> century thinking. In fact, the model of electric current and electrons
> moving in, say, a vacuum tube or copper wire, was proposed around 1900 by a
> German physicist named Paul Drude (pronounced Drood-eh). (You can google
> "Drude Model" to read about it.) Mr. Drude's theory is clever, and sometimes
> useful, but it is a result of "classical physics," and, alas, doesn't hold
> up to close scrutiny. Electrons are not tiny, hard little balls of charge,
> any more than atoms are balls of neutrons and protons with electrons
> whirling around them like tiny planets. Unfortunately, that classical
> picture, however wrong and inaccurate, is still taught in elementary schools
> and high schools, because the real picture is too abstract for young minds
> to comprehend.
>
> The description of the electrons in a metal, or anywhere else, is quantum
> mechanical. An electron in a block of copper, for instance, is described by
> something called a Bloch wave, or Bloch wavefunction (Google it, but be
> forewarned: it ain't easy to understand.), and the amazing thing about the
> electron is that it isn't localized in the copper block at all. It's
> everywhere at once in the copper, and you can't point to a specific position
> in the copper and say that the electron is there. This is not just
> mathematical abstraction. The electron really is everywhere in the copper at
> once. Quantum mechanics isn't just a model theory. It's the way the universe
> is assembled. There's probably no theory that has been so extensively tested
> and verified, thousands upon thousands of times. Unfortunately, our tiny
> brains can't visualize quantum mechanical wavefunctions very well, so we
> fall back on classical pictures to guide us, such as the idea that atoms are
> like tiny solar systems, or that electrons in a vacuum tube are ejected from
> the cathode like BBs and fly through the vacuum until they crash into the
> anode. Sorry, but that picture is misleading and wrong, even though we can
> easily imagine it.
>
> 73,
> Jim W8ZR
>
>   
>   
>
>
>
>
>
>> -----Original Message-----
>> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of K9FFK
>>
>> Electrons travel from a heated cathode or filament to the anode. Charge is
> a characteristic
>> associated with the electron (much like the color blue being associated
> with sky).
>> Electron speed in a vacuum tube is approximately equal to the speed of
> light. This speed
>> defines the transit time and thus upper useable frequency of the tube.
>>
>> Nothing travels from anode to cathode. (No protons, no positrons.)
> Residual gas molecules
>> may be ionized and end up at the cathode or the anode.
>>
>> "Holes" are a convenience tool to explain certain characteristics and
> operation of solid state
>> devices. Allowing "holes" to be equal a negative thing does not change
> tube theory. Results
>> are same, same.
>>
>> OK...flame suit on...
>>
>> Dick K9FFK
>>
>>
>> On 12/2/2016 10:52 AM, Mike Waters wrote:
>>> Thank you for your comments, Al. But in an amplifier's vacuum tubes
>>> (as Jim, myself, and others discussed earlier in this thread), are
>>> charges moving from anode to cathode opposite the flow of electrons?
>>>
>>> 73, Mike
>>> www.w0btu.com
>>>
>>> On Dec 2, 2016 10:19 AM, "Al Kozakiewicz" <akozak at hourglass.com> wrote:
>>>> Current is the flow of charges, not particles.  Charges are carried
>>>> by
>>> particles such as electrons (negative) or ions (positive), but the
>>> particle itself is not the charge.  Charges aren't a physical object
>>> that has mass or occupies space. Just like gravity - it can be
>>> measured and its effects observed and felt, but you can't point to a
> gravity object.
>>>> In the case of electrons it is most definitely NOT like a river. ...
>>> Actual electrons drift about the conducting medium at rate of
>>> something like 1 meter per hour. On the other hand the charge is
>>> propagated at near the speed of light. Negative charges flow one way;
> positive the other.
>>>> It adds nothing to the understanding and application of electric
>>>> circuits
>>> to change the convention for current flow.
>>>> Al
>>>> AB2ZY
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