Understanding voltage

Hey, I'm in 3rd year mechanical engineering and I still don't feel like I have a strong understanding of what voltage is. Maybe someone
can help explain the concept.
I'm pretty sure I understand what charge is (it's just a fundamental property of subatomic particles that affect the way they interact, i.e. a charged particle induces a force on a surrounding charged particle based on their charges (+e for a proton, -e for an electron, and 0 for a neutron) and the distance and properties of the volume between them), and I'm pretty sure I understand current, which is just moving charges (I picture a bunch of electrons moving through a volume between idle nuclei). But I don't get the concept of voltage. I know it's produced from a separation of charges, and it is energy per charge, or Joules/Coulomb, but where is the energy contained? How does the coulomb of charged particles "have" this energy, and how is it possible that there can be different amounts of energy associated with a fixed amount of charged particles (i.e. you can have 10 joules/2 coulombs = 5 volts, but you can also have 20 joules/2 coulombs = 10 volts?)?
I hope that was clear, but it probably wasn't.
Thanks,
bgold12
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Voltage is *potential* energy. The most common analogy I've seen is with that of water pressure. Think of voltage as pressure, and current as flow. Resistance is opposition to, or restriction of current (e.g. with the water analogy, a smaller diameter pipe). That's why the greater the amount of resistance, the greater the voltage you'd measure across the resistance.
-Mike
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Not quite: Voltage is NOT potential energy nor is it kinetic or any other kind of energy. Voltage is NOT energy.
Your pressure analogy is a good one however. Keep in mind that pressure is not energy either.
Voltage in analogous to pressure or force sometimes called electro-motive force, emf.
Current is analogous to flow rate.
Charge is amount or quantity of electricity.
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bgold12 wrote:

This easily yields to experiment. Try this:
Grab one coulomb of positive charge in one hand, and one coulomb of negative charge in the other. Now draw your hands apart until they are separated by 1 meter. You'll note that the force trying to draw your hands together is about 9e9 Newtons (it helps to do this test in a universe where you are many times stronger than here, and where you can hold point charges in your hands -- there may be one in your Physics building, check with a prof).
Now as you drew your hands apart, you will have noted that you had to exert force to do so, and this force was exerted over some distance -- i.e. you performed work on the charges. Solving for energy = work * distance, you conclude that you have added energy to the charges.
HTH.
--

Tim Wescott
Wescott Design Services
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Have you looked at Wikipedia yet (http://en.wikipedia.org/wiki/Voltage )? You might find that entry helpful.
The energy is contained in the electric field, more-or-less by definition: the 'field' is a region in which forces act on charges. But if you seek a physical explanation of why there should be forces at all then you may never find a clear, simple explanation, as with gravitation.
Chris
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What I can't understand is how a person can be in third year engineering and not have a strong understanding of what voltage is.
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Rose wrote:

3rd year _mechanical_ engineering. And he's working to fill in the gaps, which is more than a lot of mechanical engineering students might do.
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Tim Wescott
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It's a big gap to fill and a strange place to come to fill it.
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wrote:

Even worse... they somehow get good grades, and after they get their degrees, some of them come to work at our place, and they STILL don't understand it. Then they pay them engineering salaries and let them design satellite gear!
Working at a high voltage power supply company did allow me to review, and lock in a lot of basics. That was a good eight year experience in my life.
Especially the "one-hand-in-the-pocket" rule. :-]
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On Mon, 29 Sep 2008 14:15:17 -0700, StickThatInYourPipeAndSmokeIt

Cool. Explain voltage to us.
John
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wrote:

--
Do you also "can't understand" why he may not have a strong
understanding of what a "parsec" is, or a "millihelen", or a zillion
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At least I wasn't being cranky.
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wrote:

--
Please...

You were being much worse than cranky, you were being intentionally
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I suppose you're right.
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On Mon, 29 Sep 2008 19:43:54 -0500, John Fields

The idiot is probably an ObamaTard too.
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On Mon, 29 Sep 2008 11:57:18 -0700 (PDT), Rose

Because it's mechanical engineering?
John
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According to the California Department of Consumer affairs, the initial PE exam pass rate is lower for EE's than for any other branch of engineering. Having found the exam relatively easy, I had a hard time believing that. Nevertheless after seeing many of the posts on this subject, I am no longer surprised.
Bill
--
Private Profit; Public Poop! Avoid collateral windfall!

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My brother in law is a ME. He thinks banging the mouse on the desk helps speed up the computer.
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wrote:

I'd bet that is not what he thinks, nor id that why he does it.
Feel lucky that he doesn't go full on bi-polar on you... literally.
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On Sep 30, 6:14pm, StickThatInYourPipeAndSmokeIt

He has. Many times.
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