Conventional current 1

[renzodelfabbro]

I have studied on italian and english books at university
and I have always found the universal use of "conventional current" ( from + to - )
Now I see lots of web pages use the real electonic flow
(from - to +) so I'd like to know if there's a new trend in the university use.
Thanks

 

[beghtesady]

There is really no difference between either convention. The convention of - to + has to do with the flow of holes in electronics while the + to - convention is used in power. Regardless of which convention you use, make sure that you follow that convention throughout your analysis.

 

[Lewish]

Wrong. Holes flow from + to -. Electrons flow from - to +.

I just took an University extension course in Power Electronics, some 35 years after leaving college and they still taught current flow + to -.

 

[jOmega]

Back when I was just a pup, and attending a Navy -A- school for Basic Electronics, when the issue of current flow versus electron flow was presented, there was much discussion and finally, the instructor said,

"Look, just consider it as flowing from the excess to the deficiency and you'll never go wrong.".

Never had to think twice about it since.

jW

 

[neps3]

Hi all

Potential is an accumulation of elctrons on one side of a conductor which is called the -.

Due to the movement of electrons from an atom holes are created which is short of electrons.

Electrons flow from - to +.

The standard convention, therefore for current is from + to -. I have no idea any one has changed the convention, if so, who and why.

 

[neps3]

Hi all

Now that renzodel has started the topic, could someone explain why when a DC voltage is applied there is only a current flow intially, and when you apply an AC voltage there is a continuous current flow.

A technical explanation would be appreciated.

Regards

 

[neps3]

Hi all

The topic is across a Capacitor. DC Voltage and AC voltage.

 

[DanDel]

kantor, DC voltage across a capacitor will cause just enough current to flow to charge the capacitor to the DC voltage applied. Since an AC voltage alternates direction, it causes repeated charging-discharging based on the frequency and the capacitance(among other things) in the circuit.

 

[neps3]

Dandel

Excellent. You have a strong foundation.

With due respect to others, I have met a few people who lack this understanding.

Thanks and regards

 

[Lewish]

kantor, holes only move in a semiconductor. If you look at copper wire, during current flow, you will find that the only thing moving is the electrons.

Texas Instruments photographed electron flow in copper and hole flow in semiconductors back in the 70s.

As they say, a picture is worth a thousand words, and this put an end to most discussions of how current flows. Obviously a few of you younger people haven't seen or heard about this.

 

[neps3]

Lewish

I think you have misunderstood me. The physics of electricity is that electrons move and not holes. The definition of hole is "loss of electrons in atoms" and positively charged. This is in semiconductor theory. NPN / PNP transistors explain the theories. Have you read on electrostatic precipitation theory.

My question was on Capcitors. In the electricity theory we study as electron movement and not hole movement.

Just consider a DC Battery.

I would be very happy to investigate the theory of "hole" movement in semiconductors. Have you got any related articles from Texas on this phenomenon.

Regards

 

[Aranrhod]

If you use - to + current flow convention then the handedness rules for magnetic circuits will reverse - you will have the left hand dynamo rule and the right hand motor rule.

 

[IRstuff]

Hole movement in semiconductors is discussed in pretty much every semiconductor physics book.

While "holes" appear to be simply the lack of electrons, they move in different energy bands and have different effective masses and mobilities. This is reflected in the saturation current characteristics difference between n-channel and p-channel MOS transistors. TTFN

 

[renzodelfabbro]

Hi All ,
mine was just a "statistical question"
for know if there is some tendence in the new physics books
or courses, tired to follow the Franklin convention,
to use the real electrons movement in a solid conductor.
...so what can U tell me about university books and courses?
Thanks

 

[peebee]

The Franklin convention (+ to -) is still used about everywhere, while it's also still taught that this is actually backwards from reality, and holes can be useful in semiconductors.

Nothing's changed, it's still all taught the same way.

 

[neps3]

Hi all

The atomic theory has now been defeated by stating that holes move. The matter is a formation of nuclear bonding and the free electrons in some elements when lost they are said to be positively charged. The electron movement appear to indicate that holes move.

Nuclear fusion/fission??

Just as an example,

If I state that the mass of earth is increasing, would someone agree with me? Well you can figure out the reason.

For the earth to pull out of the sun's gravitational orbit it may take millions of years, Yeah?

Regards

 

[neps3]

Hi all

I would be happy if someone gives me a reference where it states that holes move in semi-conductors please.

 

[peebee]

This is a very difficult subject to research kantor, as the science of semiconductors is only SOMETHING LIKE 60 YEARS OLD!

Why don't you try a Google search on "semiconductor holes electrons", the FIRST LINK THAT POPS UP GIVES A PRETTY GOOD EXPLANATION.

 

[SidiropoulosM]

Let's not confuse what we must do in (a) circuit analysis and (b) in physical analysis:

(a) Circuit Analysis: you will get the correct answers regardless of what convention you use, as long as you use the same one throughout your work. I always assume that current flows from + to -.

(b) Physical Analysis: the use of a convention here is not advisable, it may lead to confusion and incorrect results. It's best to determine the flow of the electrons in each case according to the laws of physics. Michael Sidiropoulos

 

[neps3]

peebee

I noticed in a Siemens link they have explained as follows:

Looking at a conductor with current flowing away from you, the flux is anticlockwise.

This is not how we were taught unless the teachers were ignorant. We were taught that the flux is clockwise (corkscrew rule).

Any comments.

The hole I am refering to is a positively charged atom and current flows from + to -.