Ohms...

[Kedas]

YT2095 said in post #24 :

allowing an electron to be MEASURED will draw current

 

First something else:

Hip hip hurray, I received my first email notification from this forum.

 

I still don't understand your question.

What do you want to measure its position its speed? and with current do you also mean the movement of electrons in a metal to one side because they are attracted to it or do you only say current when we have a

closed constant current loop.

[YT2095]

it`s existance.

[VendingMenace]

so you content that measureing any property of an electron must also draw current?

 

(i say any, becuase if an electron has any measurable property, it must also exist. SO measureing any property is the same as finding out that it exists)

 

i think we are treading into a quagmire here. For one, talking about individual electrons and current makes little sense, since current is a bulk property. Second, once we start talking about single elctrons we are now in the relm of QM. Also, electrons are always moving. The uncertainty priciple insures this. Thus, if we are going to talk about current, we need a better definition for this discussion.

 

Anyways, just my thoughts, if we are going to talk about this more, we need some definitions...

 

I would suggest the following...(but give me your thoughts too)

1) Current -- the net movement of a "significant" amount of electrons in a definite direction. (significant being "more than two??)

2) Measurement of an electron -- measurement of any physcially observable property (since we are talking about voltage the relevant ones would seem to be charge and position)

 

 

Anywyas there is a start. Also, YT could you try to phrase your assertion as unabiguously as possible? Are you trying to say that voltage cannot exist without current? Are you saying that all measurements require movement of electrons? Are you merely saying that we cannot currently contruct in ideal device? I must admit i am having trouble understanding your position as well.

 

Cool

[YT2095]

All practical measurements require electron movement.

There is NO "ideal Device" to get around this.

 

and the movement of any electron or group of electrons, will result in current flow (and as a side note, a magnetic feild).

I did consider my above post quite clear (at the time and in context) I`ll have to read back I think, and then see if I can explain any better, if I can I shall

[Kedas]

about definitions I would go for:

Electron movements:

When the average displacement of electrons is different from zero based on the highest probable positions.

 

Current:

continuously and/or periodical electron movements.

 

This should help us having less confusing talks.

 

about measurring electrons/E-field (voltage).

The voltage between A B is equal to the electrical field strength integrated from A to B.

and Voltage is Q (charge, the amount of electrons) devided by the capacitance (between A B).

 

P.S. I wasn't able to post for a few day's. (forum/PC problems)

[YT2095]

Kedas, you`re not on your own, I wasn`t either

and now that I can, I find the quick links at the top are missing and replaces with a series of dots?

 

looks like it maybe a few teething probs during the server transfer... not to worry though, it`ll get sorted I`m sure

[VendingMenace]

yeah, i wasn't able to post either, which was a bummer, since i was enjoying this discussion

 

lets see if in can remeber what i was going to say...

 

and the movement of any electron or group of electrons, will result in current flow (and as a side note, a magnetic feild).

 

the movement of only one electron becomes problamatic and we must be careful in our definitions. The reason being that current is usually a measure of how much charge desity move past a certain point in a given amount of time. SO what we do is find a point along a circut or whatever and then see how much charge moves by in a given time. With at least 2 particles is not a porblem (even though it may be kinda crazy to do, since n=2 is a poor sample size, but i digress), however, with one electron we are presented with a problem. This problem lies in the fact that an electron is considered a dimensionless particle. Thus, an electron can pass by a point in no time at all. Thus, when we talk about a sigle electron, we find that a finite amount of charge (1 eV) can pass by a point in no time at all. Thus the number given by charge over time is infinity. Thus for only one electron we must find that our current is infinite. This of course makes no sense and that is why it is improper to speak of current when only considering one electron. Current is a property of more than one thing -- as it is really a statistical value. In fact, most often in is spoken of as a bulk property and requires many electrons moving.

 

Of course this may be somewhat nit-picky for this discussion. I am unsure now what we are talking about. Are we saying that voltage nessesitates current or that mesuarement of things require movement of electrons?

 

And we must decide what constitues movement of electrons, i thnk that kedas is on to something with his definition

 

When the average displacement of electrons is different from zero based on the highest probable positions.

 

how about we just say, when an electron is displaced from the position (or state) in wich we would expect to find it, given no outside influence? I think that is quite close to what you were saying, kedas. But your definition is fine too.

 

One last thing i want to ask. Are we working soley in the realm of what we can make in this world at this time, or can we use theoretical arguments. I ask only becuase of this;

 

All practical measurements require electron movement.

There is NO "ideal Device" to get around this

 

I must admit, this made me smile NOt really a theorist, are you YT? But that is cool. Will you accept as true something that is currently only true in theory? Or must we be able to build it today in order for it to be applicable to this discussion? Just curious, becuase you will not hear me say that we can build an ideal device, just that conceptually one can exist.

[YT2095]

If you look at standard electrode potentials, you may say you have a lump of material A and material B and electrolyte C.

 

put together they will generate a voltage and current under load.

 

if you attatch a voltage meter , 1 probe to each lump of material there will be no voltage pressent.

although both would be more than willing to exchange electrons in a suitable medium ©.

A maybe very electo Positive (A) and (B) very electro Negative, and so in their own right with have electrons in motion, but will not create a flow and nor could it be said that there is a "voltage difference" between them.

 

as for the post when I mentioned "work" being done and then was quoted "static electricity and/or lightening" LOL

what makes the Crack sound when you get a static discharge touching a car door in the summer? or what burns out or guts a tree when hit by lightening? I`ll tell you... CURRENT!

[Kedas]

YT2095 said in post #33 :

If you look at standard electrode potentials, you may say you have a lump of material A and material B and electrolyte C.

 

put together they will generate a voltage and current under load.

 

if you attatch a voltage meter , 1 probe to each lump of material there will be no voltage pressent.

although both would be more than willing to exchange electrons in a suitable medium ©.

A maybe very electo Positive (A) and (B) very electro Negative, and so in their own right with have electrons in motion, but will not create a flow and nor could it be said that there is a "voltage difference" between them.

 

out or guts a tree when hit by lightening? I`ll tell you... CURRENT!

 

- You are still confusing the difference between the fact that the voltage is present and the fact that measuring it will influence it more or less (depending on how ideal your device is)

BTW attaching a voltmeter between them will most likely just have removed the present static voltage)

 

- lightning: I was obviously referring to the situation before the discharge.

(BTW the current doesn't make the sound it's the heated air that does that)

[Kedas]

VendingMenace said in post #32 :

And we must decide what constitues movement of electrons, i thnk that kedas is on to something with his definition

 

how about we just say, when an electron is displaced from the position (or state) in wich we would expect to find it, given no outside influence? I think that is quite close to what you were saying, kedas. But your definition is fine too.

 

What continuous:

with that I wanted to refer to DC, leak current,etc.

with periodic:

I wanted to refer to AC, antenne current,etc.

 

"would expect to find it"

Gives a lot of room for interpretation here. I don't like that.

with 'based on the highest probable position' I want to exclude movement that is based on unlikely statistic-chances. (we wouldn't get anywhere if we include that in the def.)

[VendingMenace]

"would expect to find it"

Gives a lot of room for interpretation here. I don't like that.

 

no problem

 

with 'based on the highest probable position' I want to exclude movement that is based on unlikely statistic-chances. (we wouldn't get anywhere if we include that in the def.)

 

agreed. The movement of the electron must be do to outside forces and not from the time-evolution of its state.

[YT2095]

ok, the heated air makes the sound, but what heated it? Current