Ohms...

[KHinfcube22]

I didn't know if this would go under Computer science or Mathematics...Oh well...

 

Ok, you all know that the Ohms Law states Ohms=Volts/Amps; Amps= Volts/Ohms; and Volts= Ohms*Amps...

 

Well, say one tries to run 5v through a wire with 0a...What would the Ohms be?...General Mathematics would say it is not possible, seeing how one cannot divide by zero, seeing how zero times anything is zero...With zero itself as an exception...Well, me and a friend have come up with that since the current of the wire is zero, than the resistance, (Ohms) must be indefinite, absolute, and furthermore, infinite...Thus, V/0, seeing how the number of volts is irrelevant, would equal infinite...Also stating, infinite times zero must equal a whole number, thus proving that something times zero can equal a whole number...But also, there must be more than one number that can be multiplied by zero to equal a number, or the number that is multiplied has a variety of things it can equal...I'm confused...I am not in a high enough math at the moment to understand what the answer to my problem is seeing how I'm only in geometry...Can someone please tell me in a way I'd understand what the answer to what the Ohms is...Also, is there anything that has zero current, and absolute resistance?...And if there is, or even if there isn't, what is/would-be the atomic structure of this mysterious metal?...Oh well...

[iglak]

well...

nobody knows what you get when you divide by zero, but my personal hypothesis is that it is "everything". "everything" is not known to math. "everything" is not infinite, it is not a neverending series of numbers, it is all numbers at once.

 

but about the resistance/voltage/current thing

0 current means that 0 electrons are passing through. this means that 0 voltage can be transferred. so i suppose the resistance would either be "everything" or infinite.

[Kedas]

V/Inf=0 --> V/Inf*Inf=0*Inf (both sides are undefined)

Not --> V =0*Inf.

[VendingMenace]

well, as far as zero current goes, that means that there is no flow of electrons through the material. Since there is no flow of electrons through the material, then it is kinda pointless to talk about the resistance that those electrons encounter.

 

 

I guess what i am trying to say is that, the concept of resistance makes no sense when there is no current.

[KHinfcube22]

Ummmm...This went a bit farther than I thought it would...As those have said, the voltage of something is not dependent on current, otherswise we couldn't have something to store voltage in the first place, except some kind of circut...Which would eventually drain itself out of power...Oh well....

[YT2095]

You can`t have voltage without current, no matter how miniscule that current may be, it would still be present.

it would be like trying to calculate speed without using distance traveled or time in your equasion

[Kedas]

You CAN have voltage without current OF COURSE.

example all static voltages.

(including lightning)

[YT2095]

sorry, that`s technicaly incorrect, there is no currenet without voltage and no voltage without current, how else could it make a circuit? or do WORK?

[VendingMenace]

i am going to have to side with kedas here. You can have voltage without current, at least theoretically.

 

A picture that many people use to think about amps (current) and voltage is the idea of a waterfall. Since voltage is really potential energy, people equate the heigh of the waterfall coresponds to the voltage. Now current is a measure of flow of electrons, so people equate the amount of water going over the waterfall to the current (makes sense). NOw using this example, we can see that the height of the waterfall is not dependent on there being water flowing. It has heighth regardless. Likewise, voltage does not require amps.

 

Perhaps another way to think about it is just to remember that votage is potential energy. Thus, it does not require anything else -- no other form of energy or movement. Just like a book does not have to fall from a table in order for it to have had gravitational energy.

 

how else could it make a circuit?

 

Well, i guess it depends on what you are talking about when you say circut. Do you just mean a closed loop? Then there is no need for current. But if you mean something in which there is current, then of course something without current is not a circut. But just becuase it is not a circut does not mean that it doesn't exist.

 

or do WORK?

 

Well, like i said above, votage is really potential energy. So it doesn't do work. If it was going to do work, then it would need a current.

 

 

I guess all in al what i am saying is that it is theoretically possible to have voltage without current. Of course, it is quite difficult to achieve (if not impossible, currently), but it is still a theoretical reality. So in then end we find that; practically, perhaps you can't, but theoretically, it is possible to have voltage without current.

[YT2095]

tell me, how do you measure the pressence of voltage without drawing current?

 

make me a beleiver )

[Kedas]

How to measure: measure electrical field.

A simple mosfet wil do.

The gate doesn't draw current and a voltage on it is very noticeable on the drain source current.

 

There is leakage but doesn't change the idea/working, with a perfect isolation it would still work.

 

MOSFET: Metal-Oxide-Semiconductor- Field-Effect-Transistor

[YT2095]

for 1 single electron to trip the Gate between A and K will draw current, sorry.

 

and there`s no such thing as "perfect issoltaion/insulation" with the exception of a perfect vacume and a perfect radiation sheild between it.

[Kedas]

So what you are trying to say is that it's not possible to measure an electrical field without changing it's potential/voltage.

 

Do you know a device called an electroscope?

http://www.engr.uky.edu/~gedney/courses/ee468/expmnt/escope.html

electrical field is 'measured' without even one elektron jumping.

 

What do you mean with 'perfect radiation sheild' you want to measure it but not detect it ???

 

BTW air is also a perfect isolator until the elektrons jump because the voltage/force is to big.

[VendingMenace]

tell me, how do you measure the pressence of voltage without drawing current?

 

well, i don't quite see what this has to do with voltage existing?

 

Let's give you the benifit of the doubt for now and assume that you cannot measure voltage without drawing current, ok? So now, we can never measure voltage without drawing current, does this mean that voltage is dependent on current? Does the voltage difference not exist until we measure it? This doesn't seem to make sense. We know that votage is just a difference in charge, esentailly. Thus, if we assume that voltage is dependent on current, we are saying that there can be no charge difference if the charges are not moving?

 

make me a beleiver

 

i don't really know what else to say other than the equations for voltage do not tell us that voltage is dependent on charge (i wish i had a physics book with me). Thus, we know that theoretically there can be voltage without current. That is a fact that is given to us by the equations.

 

Of course, like i said earlier, i don't know if this can be practically realized. There is always leakage. Since it cannot really be practically realized, there may not be a way to measure voltage that will ensure that there is no movement of electrons.

 

One way we could test for the absence of current is to take a capacitor and measure the magnetic feild around it. If it was an ideal capacitor (no current between the plates) we would observe to magnetic field, despite the fact we know the plates are charged. WE would be forced to conclude then that there is no current, even though there is voltage.

 

I would like to stress again though, that your requirement for a way to measure voltage without inducing current is not a very strong argument. Basically, it asks for proof of an idea using less than ideal instrmentation. If you want proof of an ideal you must look at the idea (found in the equations)

 

WEll, hope that helps some

[YT2095]

"Of course, like i said earlier, i don't know if this can be practically realized. There is always leakage. Since it cannot really be practically realized, there may not be a way to measure voltage that will ensure that there is no movement of electrons."

 

there is indeed NO WAY to measure voltage without moving electrons, and by doing so, there will be current

 

sure one may do this on paper and say I have a battery here that I have drawn/designed and it will have 10 Volts across it`s terminals, and indeed this paper battery will on paper last forever, and were you to measure the voltage of it in maths, it would be correct

but in REAL TIME, this is not possible

[VendingMenace]

but in REAL TIME, this is not possible

 

agreed, in the real world it is not possible. However this does not mean that votage is somehow dependent on current. THat voltage cannot exist without current. There is absolutely nothing that keeps us from having a perfect battery except our innability to design one. That is to say, there is no reason why voltage could exist without current, we just can't make something that does that right now.

[Dudde]

I'm too tired to read all that, but I just want you to think about the fact that you're trying to calculate resistance to something that isn't there

 

...

 

 

EDIT: and how the freak are you going to get voltage without current? voltage depends on the current?

[Kedas]

BTW you say: 'there is no perfect isolation with the exception......'

It is possible to make a 'mosfet' that way but I doubt they will do it to please you.

 

You also seem to have drifted from your original point of view to an other thought problem. (Keeps us guessing what it is you don't understand)

 

Saying 'current can't exist without voltage' is like saying static electricity doesn't exist (independant if you can measure it or not)

[Dudde]

dangit, I just typed that whole stupid thing out...I hate this computer

 

anyway, how are you getting voltage if there's no flow of electrons (electricity?) ?

flow of electrons : voltage

flow of electrons = current

current : voltage

 

or something like it

I don't know, I'm going back to read up, cause I forgot a few things I think...

[VendingMenace]

voltage = difference in electric potientials (usaully charge)

current = flow of electric charge

[Kedas]

on the first day there was voltage.

on the second day He created current.

 

It's like saying force can't exist without moving.

[Dudde]

well how the hell do you get the difference in electric potentials if there's no electricity??

[YT2095]

"It's like saying force can't exist without moving. " Ewwwww that`s almost worthy of a thread in it`s own right!

 

I`de contend that force cannot exist without movement of some sort as well

but I digress....

 

Kedas, your MOSFET arg is flawed though your correct that it takes very little current in comparison to a transistors BASE to allow secondary current flow, the gate in a MOSFET will also need electron flow (albeit very tiny compared) to set up the Feild in the P or N substrate.

 

think... what sets up the Feild in a Feild Effect Transistor?

[Kedas]

YT2095 said in post #22 :

"

think... what sets up the Feild in a Feild Effect Transistor?

 

everything has a little capacitance so you will need to move those electrons to put that voltage there.

How the voltage came there in the first place is beside my point it was only to show that the present potential can be measured by measuring it's electrical field.

 

And measuring voltage without letting one electron move is never possible because electrons are moving all the time in metal. So it's a bit like saying measure gas pressure but without letting molecules move. They are already moving before you start.

[YT2095]

ok then fair enough point, allow me to rephrase it then (I thought you understood my meaning).

 

allowing an electron to be MEASURED will draw current

 

that should be better