conventional current or electron flow

[faradayfan]

conventional current

How should I look at circuits, as conventional current or electron flow current? Does everyone here analyze circuits based on conventional current flow? Forgive me I'm an electronics noob.

 

[akshay_d_2006]

conventional current flow

One should always analyse circuits on the convectional current flow. This is because all the Laws (KVL, KCL and other higher laws BJT Models) are analysed ( And given appropriate signs) after considering that the current flows in the convectional direction.


However when you study particulat element in circuit ( say capacitor or a transistor, MOSFET, JFET) and when you need to know the electronic flow to understand some causes and conditions, you should consider the electronic flow.

**Electronic flow and convectional flow are always in opp. dir.

 

[faradayfan]

what is conventional current

Thanks. So would it be true to say ANY circuit behaves as if conventional current flow was exactly the same as electron current flow?

 

[Infinytus]

conventional current vs electron flow

We always consider conventional current's direction for analyzing various circuits. The direction of conventional current is opposite to the flow of electrons. But we have adopted the opposite direction as a convention and have been using for all the laws, thats precisely the reason why it is called the conventional current.

The conventional current is not a physical thing, its just used for analyzing circuits. But on the other hand the current produced by electron flow is a physical(meaning it exists) thing, whose direction is opposite to that of conventional current.

Regards,
∞ :idea:

 

[akshay_d_2006]

conventional vs physical current

Dear faradayfan,

Electronic current and convectional current are two completly different things.

Try n understand this:
Consider a metal piece. It has lattice-(An arrangement of points or particles or objects in a regular periodic pattern in 2 or 3 dimensions) structures and has free electrons on them. they move throughut the metal but are bounded to the metal lattice. These electrons move in any random direction due to thermal energy, However their net movement is zero.
It means that the no. of electrons flowing from 1 sidt to other are equal to the no. of electrons flowing from opposite side to cancel eachothers mvement.

now when a potential diff. is applied betwn 2 sides then all the electrons are allinged and start to move towards the positive side ot the battery. since electrons are -vely charged they are attracted towards the +ve terminal.

In this Process an electron or two gets isolated from the metal lattice and diffuse towards +ve terminal leaving no charge where it was initially present. (this no charge is called as +ve charge or a hole.

So if we assume that electrons are moving from Left to right then one can imagine the holes moving from right to left

Since in convectional electronics we assume all the charges to be positive(eg. test charge is always +ve) we consider the direction of +ve charge (hole) moving as convectional current direction

[/b]

Added after 13 minutes:

Thanks. So would it be true to say ANY circuit behaves as if conventional current flow was exactly the same as electron current flow?

No, It would be wrong to say that All circuits behave in similar fashion if convectional current was same as electron current flow. Because

1) First and fore most both the directions cant be same.
2) Consider an element capacitor in an circuit:

All the current directions taken in problem solving are convectional directions. And the following eg. will prove itself.

+ -
-------->----------------||------------
(current) (capacitior)

The dir. mentioned is convectional dir. that means electrons are flowing in opp dir. which is proved by seeing the polarities of the capacitor. When electrons hot the capacitor (Right plate of capacitor) ther being -ve induce -ve charge on the plate.
Thus it is proved that electrons were flowing from right to left and convectional current from left to right.

In problem solving if v dont know the current flow assume any dir and if that dir was true you will get +ve ans.
Else you will get -ve ans and then just reverse the dir.

Added after 2 minutes:

But we have adopted the opposite direction as a convention and have been using for all the laws, thats precisely the reason why it is called the conventional current.

∞ :idea:

The convectional current direction supported all the theories and laws postulated so it has been assumed as the direction in problem solving.

 

[faradayfan]

conventional electron flow

So when analyzing a circuit using formal methods conventional current is used, but is this the way people in electronics look at circuits when they are just trying figure it out informally? It seems to me if conventional current works theoretically it is best to stick to just that method and not confuse the issue.

Maybe I should rephrase my previous question; if you analyze a circuit assuming conventional current flow will you always be correct, assuming of course you didn't make any mistakes.

 

[LvW]

convectional current

.............
Maybe I should rephrase my previous question; if you analyze a circuit assuming conventional current flow will you always be correct, assuming of course you didn't make any mistakes.

Yes, you are right. However, just for clarification: by analyzing circuits it is NOT necessary to assign the "correct" direction before starting calculations based on voltages and part values. You can, instead, assume any direction for the branch currents - and if the result for a specific current turns out to be negative, you know that your first "intuitive" assumption for the direction was not correct and has to be inverted. Thats all.

 

[akshay_d_2006]

benjamin franklin on conventional current flow

Yeah true.
I had mentioned that though..

Conclude: Analysing ckts-Convectional Current
Analysing Ckt elements -(When not present in ckt)- sometimes use electron flow.

 

[flatulent]

conventional vs electron flow

As a piece of history, we owe the positive current flow to Benjamin Franklin who got his kite experiment data and made a bad guess at the current.