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Basic Electronics » Which way does electricity flow? Positive-to-Negative or Vice Versa?

July 21, 2011
by rboggs10
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Wow! Just a few minutes ago I got majorly confused. I have been playing with electronics for about 7 months now and always had the idea that electricity flowed from positive to negative but just now came across an article that says it flows from negative to positive. Can someone please shed light onto this subject for me?

July 21, 2011
by Ralphxyz
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Benjamin Franklin said electricity flows from positive to negative.

So no one questioned it, after all he is the "inventor" of electricty.

Eventually some really smart guys determined that it actually "flows" from negative to positive.

I am still at the point in my understanding of all things electronics that I really do not care.

There are pictures now showing lightning flowing up from earth to the sky which are really fantastic.

Ralph

July 21, 2011
by mongo
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Original thought was from positive to negative. That's how they got the + and - designations. However, back then they really didn't know that electrons even existed. They were later named for their phenomena rather than the other way around. Electricity is named for the Greek Goddess Electra, Goddess of the storm clouds, which is the source of lightning. As it turns out, the flow is a mutual transfer of electrons and "holes" which become receptive to electrons in the electrical field. They do come from the negative and flow toward positive. Electrons are a negatively charged subatomic particle. This is especially important in solid state electronics where doping creates these "holes" in the substrate, making it conductive in one direction. (a diode works like that) diode link The holes are not necessarily always there but in electronics, they are fundamental. In nature, electrons flow pretty well without the holes.

Here's the cool part. When you pump an electron into a conductor by completing a circuit, that electron does not necessarily come out the other side. Billions of other electrons would likely transfer out before that one ever sees the light of day again, if ever. They act like billiard balls in a sense, where the chain of electrons transfer from a valence of extras to those without. As long as extra electrons are available, they continue to flow, provided there is a place to go.

Electrostatic fields are the extra electrons with no place to go. Since they can't transfer into a conductor without a return path, they rest on the surface. Being there, they can be transferred readily until the differential is equalized. (usually with a spark, as they can be fairly high in potential, like walking across the room and getting zapped when you reach for the door knob). Being a surface charge, electrons can also sit on an insulator surface, like a balloon. A capacitor is an electrostatic device.

A Van de graaff generator is an example of surface charges, both with abundant electrons and shortages. Electrons are taken from one source, transferred via a non-conductive moving media surface and released to the receptor, The top is round for a reason. It has a large surface area where the charge can build up. If the other half of the circuit comes in proximity, the electrons jump from the sphere to the ground, returning the electrons to their original place where the shortage existed, equalizing the differential.

July 22, 2011
by bretm
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Yes, electrons flow from - to +, but electrons and electricity aren't the same thing. In metal wires it's the electrons that move, but inside the battery it's entire charged atoms that move, both positively and negatively charged. http://amasci.com/amateur/elecdir.html has a good explanation of this. Electricity flow direction is just a matter of convention and agreement. The physical reality is that charges of both polarities flow in both directions depending on the materials and circumstances.

July 22, 2011
by rboggs10
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Thanks for clearing this up for me.

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