Direction of Current (1 Viewer)

[Viper]

Hey all,

Just a quick one... For a while i have understood that in a conventional current, the electrons move from the negative terminal to the positive terminal? Is this correct?

Are there any cases where the electrons DO NOT travel from negative to positive?


Cheers

 

[Huy]

Originally posted by Viper
For a while i have understood that in a conventional current, the electrons move from the negative terminal to the positive terminal? Is this correct?

No, conventional current goes from positive potential to negative potential (the other way around, as you've described it).
From + to -

Originally posted by Viper
Are there any cases where the electrons DO NOT travel from negative to positive?

Electrons (being negatively charged) will flow in the direction which is opposite to conventional current (from - to +, being attracted to the positive potential).

So no, electrons will always move from - to +
And conventional current goes from + to -

 

[Viper]

Thanks *Huy*, this might be another stupid question, but what is the difference between conventional current and electron flow then? Im getting a bit confused?

Cheers

 

[Huy]

Electron flow = the direction of electron drift/movement, this is from negative to positive (see above post)

Conventional current = I have no idea, but I know it's positive to negative because it goes from positive potential to negative potential.

Current goes one way, electrons go the other way.
(The movement of electrons = current)

Other than that, I only know the syllabus

 

[Dash]

Ok... that confused me

Just read the textbook Viper, it should be all there...

 

[Fosweb]

Faraday was an idiot. He said current was positive to negative. And since he stuffed up - we suffer and get confused. (someone should just unanimously decide to change it now on behalf of all physics people.)

So CONVENTIONAL current is the APPARANT flow of positive charge (since positive charges dont actually flow - they stay stuck where they are and the negative charges flow.)

ELECTRON current is the flow of negative charges.

In chemistry - current is electron flow. In physics - current is conventional current.

 

[Viper]

So in a motor, do we state the conventional current or the electron flow???

Cheers

 

[BrotherMerry]

we always use conventional flow. at least i do. and i have been known to be a chump...no, i'm almost entirely positive we use conventional flow.

PS yeah, that was supposed to be a pun...i'm so lame...

 

[Rahul]

Originally posted by Fosweb
Faraday was an idiot.

haha, that sounded funny

i am pretty sure that in a motor its a conventional current.

 

[deyveed]

What about the cell symbol in a circuit (the |i|i things)? Which one does conventional current come out of?

Also, which topics usually talk about electron flow and which talk about conventional current?

 

[Fosweb]

In physics - it is always talking about conventional current unless it says "Which way do electrons go" or something like that.

<--- (+) |i|i (-) --->

 

[-X-]

Isnt conventional current the "movement" of the holes?

 

[Huy]

Originally posted by -X-
Isnt conventional current the "movement" of the holes?

You're thinking of doping and semiconductors (9.4 from ideas to implementation), P-type and N-types.

Or maybe that's what I thought you were on about... "movement of the holes", 'positive' hole formation, free electrons moving into the conduction band, etc.

 

[-X-]

ahh yes. lol

 

[stag_j]

in conventional current don't think of it as holes, think of it as positive charges moving - ie. the protons moving instead of the electrons. we now know that this isnt the case, but back when faraday did his work he assumed that it was the positive charges that moved.
you can state an answer either way, but make sure you clearly identify which you are talking about. diagrams in textbooks/exams are always given in conventional current, even if this is not specified, so it is a better idea to give your answer in terms of this too. and remember that when using the right-hand-rule, etc you are talking about conventional current, so if you're dealing with electrons you need to use your left hand.

 

[-X-]

So reallly, there is no such thing as conventional current right?

 

[deyveed]

Could someone explain how semiconductors are used and work?
Ok. Is it true that a plain old semiconductor like silicon does not conduct electricity but when doped with group III or V it can?
Does it need a p-type and n-type to be connected to be able to push an electron into the p-type part and then conduct electricity?
Can it electricity flow in just a p-type?

 

[Rahul]

Originally posted by deyveed
Could someone explain how semiconductors are used and work?

I'll try

Originally posted by deyveed
Ok. Is it true that a plain old semiconductor like silicon does not conduct electricity but when doped with group III or V it can?

I believe it doesnt conduct as well if it isnt doped. thats the whole reason they are doped.

Originally posted by deyveed
Does it need a p-type and n-type to be connected to be able to push an electron into the p-type part and then conduct electricity?

No. They can work individually, ie- a p-type or n-type can conduct electricity on its own. Just their mode of conductivity(?) is different; p-type the electrons jump from hole to hole and in the n-type the extra electron in the conduction band is used to conduct electricity.

Originally posted by deyveed
Can it electricity flow in just a p-type?

I think the last bit answered that.
HTH

 

[Dash]

Wheres wogboy???

Normally at this point in time he would come here and post his mad ass explanations

Hmmm *waiting*