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Basic Electronics » Evil battery polarity +/- understanding the basics

July 30, 2009
by luisgarciaalanis
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Hello guys,

So I see that we connect our circuit to a battery and the ground is connected to the negative pole of the battery. However Protons don’t move since the atoms don’t move. So in reality the current is flowing from the ground to the positive pole of the battery?

Going back to the basic LED circuit http://en.wikipedia.org/wiki/LED_circuit

“An anode is an electrode through which electric current flows into a polarized electrical device”. The LED has an Anode and a Cathode. On the LED circuit the Anode is connected to the positive marked terminal of the battery does this mean that the positive marked terminal on the battery really the negative pole of the battery (where the electrons flow from)?

Which way is it, why does the battery seems to be marked backwards?

Thanks Luis

July 31, 2009
by wayward
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Hello Luis,

you're right, you did spot a little inconsistency that's as old as Benjamin Franklin (I think he's actually responsible for labeling the terminals so). Perhaps it made sense to have something move from where there's an "abundance" (+) to where there's a "lack" thereof (-), before we understood protons and electrons.

But how about this: every electron that leaves an atom, leaves behind a potential "hole" of positive charge. Now if electrons move in one direction, those "holes" will appear to move in another, even if only as an abstraction. So in reality we actually have two flows of current: electrons, from (-) to (+), and "holes" from (+) to (-).

If you can understand this, you'll have no problems understanding how diodes and binary junction transistors work, when you decide it's time to tackle principles of semiconductors!

Cheers, Zoran

July 31, 2009
by luisgarciaalanis
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I see your point about a positive charge, but remember protons don't move.

As a charge it makes sence that you have two flows. But if you are like transmitting audio allong with the current (like in an Amplifier) then it has to be on the electrons.

The problem is that every reference I seem to find point out to the batery (-) pole sending the electrons to the (+) and that does not make sence because for example the Anode on the simple led circuit from the wikipedia is connected to the (+), but perhaps its the ficticial (+) current that is entering the anode, and what about caps instead of storing electricity they loose electrons... its just wierd.

http://www.youtube.com/watch?v=1xPjES-sHwg http://www.youtube.com/watch?v=EJeAuQ7pkpc&feature=fvw http://www.youtube.com/watch?v=D2monVkCkX4&feature=related

Videos seem to point out to the - is the place from where electrons come out from.

http://en.wikipedia.org/wiki/LED_circuit

is the LED anode actually a positive current anode or is it just that the battery videos are wrong? also anodes are marked as (+) because they should attract electrons.

Stupid Benjamin!

August 01, 2009
by wayward
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True, but in some way, it is not incorrect, because a kind of positive charge does flow from anode to cathode -- only it's not carried directly through electrons, but rather through absence of them. Electrons are majority carriers in metals, but in some other (semi)conducting substances, positive ions might well be mobile carriers for all we know (for ex. in liquids and gases).

August 05, 2009
by BobaMosfet
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Luis--

You are being confused by the fact that there are two (2) ways to look at electronics.

  1. Conventional Flow - Power flows from the (+) side of the battery, or
  2. Electron Flow - Current flows from the (-) side of the Battery.

Electron Flow is how the physical world REALLY works. Conventional Flow is simply how Ben Franklin LABELED it. Had he known electrons flows from - to +, he would have labeled it differently.

So, using your LED example: ALWAYS connect the Anode side to the (+) side, but understand electrons flow from the Cathode side to the Anode side.

You have to learn how to use both Flow methodologies correctly and a way to keep them straight in your head.

wayward- ions are electrons according to Merriam-Webster Definition 2.

August 05, 2009
by wayward
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All ions are electrons? I was told in school that any atom or molecule with a non-zero total charge is an ion (hence cation and anion, ionization, etc.) Or am I missing something?

August 07, 2009
by mongo
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Anode... Cathode... If you stick to the reality, yeah, electron flow goes against the arrows, LED's, diodes, transistors, etc.

Way back when this stuff was still a new thing, folks didn't really know which way electricity flowed, or if it actually flowed at all. It was assumed that if you give a charge a name like 'Positive", then the flow must come out of that side. Ben Franklin had no way of knowing at the time so he shouldn't be criticized for it.

Actually, the names were more or less arbitrarily given because there was still a lot to learn yet. This time, they got it a little bit backward but the names and terms stuck. The hole theory is a nice rationalization for something that works counter-intuitively but the holes don't actually move either. It only appears to be so, like the flashing lights on a Las Vegas sign, where the lights seem to race around the edges.

I just find that it is just easier to not over-think the circuit and just remember the little arrows point to where the flow comes from.

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