what exactly is Voltage

[KrisBlueNZ]

Electricity is a form of energy as is heat. Voltage is the potential difference between no electrical energy and some electrical energy.

Amperage is essentially the amount of Voltage per unit of time.

What? None of those statements is true. Especially the last one.

As for what voltage is, I can't actually explain it, although I've been an electronics engineer for 20+ years.

Voltage used to be called "electromotive force" (EMF), i.e. a force that makes electrons move, and that's true in that voltage does make electrons move, but "force" is not a very appropriate word in my opinion because to me, force is something you measure within an object - for example, if you squeeze something between your thumb and finger, you are exerting a force on it (which would be measured in Newtons), whereas voltage is not measured within something; it's measured between two points, like a distance that you measure with a ruler or tape measure.

It's also called "potential difference". This means more to me, because voltage is always a difference - it's always measured between two points. So if voltage is a difference in potential, the question becomes "what is potential?" and again I can't answer that in any useful way.

You should know about the hydraulic model for voltage and current, where water flowing in pipes represents current. Personally I don't find that model very useful, although there's a good match between water flow and electron flow. (I find electron flow an easy enough concept to understand.)

I've created my own model called the DTS model - distance (voltage), tension (current), stretchiness (resistance) which I think is good for explaining voltage, current, and resistance in common circuit configurations, but it is not at all compatible with the hydraulic model. If you're interested, search these forums for "DTS model". I want to produce a few videos on it, but my graphic design skills are not up to the task.

FWIW I think that it's not necessary to be able to explain exactly what voltage is, as long as you understand how the various quantities relate to each other; these models are designed to help you understand these relationships between them so you can design working circuits, and I think that's enough. Others on the forum will probably disagree!

 

[(*steve*)]

I think it is clear from these descriptions that the voltage is proportional to number of charges in a stationery charge object when no current (no charge flowing).

If that is clear to you then you didn't read it right.

Voltage is electric potential energy per unit charge,

Go back to my example of pushing an electron up a hill. The voltage is how high up that hill it is. If you have 2 electrons there, or 10, or a bazzilion, the voltage is the same.

The amount of energy depends on how much charge is there, so two electrons would have the potential to release twice the energy as one.

 

[kap]

thank you guys, its clear to me now,

 

[Laplace]

its clear to me now,

I would hope that what is clear is you will never find the answer you seek. Asking the question, "What is voltage?", is almost the same as asking, "What is gravity?" Nobody knows the answer to that one either.

Gravity is an observed natural phenomenon relating force and the attraction between mass. Voltage is an observed natural phenomenon relating force and the attraction/repulsion between charge. For what it's worth, nobody knows whether anti-matter falls up or down because that behavior has not yet been observed.

Seek not the certain knowledge of what 'is'; focus instead upon the quantifiable relationship of one phenomenon with another. When you understand a wide web of interactions and can manipulate these phenomena to optimize a desired result, you will have become an engineer.

 

[KrisBlueNZ]

Good answer Laplace.

I read the linked descriptions that try to explain what voltage is. I didn't find them meaningful; maybe that's because I've never been strong on physics.

I like your analogy to gravity. Everyone knows what gravity is... until we're asked to actually explain it. All we can do is describe what it does, in terms of other quantities that we can understand.

 

[BobK]

The correct analogy is not that voltage is analogous to gravity, it is gravitational potential that it is analogous to. And in a uniform gravitational field, that is proportional to height, which is the analogy Steve was using.

Bob

 

[KrisBlueNZ]

I agree Bob. Laplace's point is simply that voltage is like gravity in that they are both things that we understand through their effect, not through an understanding of what they are or how they do what they do; we understand only how they cause other effects.