# The simplest definition of VOLTAGE you can come up with

1. ## The simplest definition of VOLTAGE you can come up with

I've measured it thousands of times, talked about it hundreds of times, but never reaaaaally understood it.

All those definitions seemed so complex, as if they are trying to make the voltage seem so mysterious.

So, after a little bit of thinking, I think the simplest definition of voltage I could come up with would be:

"Voltage is the difference in the amount of electrons between 2 (or more) points."

What do you think? First of all, am I mistaken? If I am, how so?

How would you explain voltage in the dumbest terms possible? •

2. ## Re: The simplest definition of VOLTAGE you can come up with

The force electrical charges are pushed in order to circulate. 3. ## Re: The simplest definition of VOLTAGE you can come up with

Hi,

You may compare voltage of an electrical system with pressure in a hydraulic system.

Preassure makes the oil to flow. Voltage makes charges to flow = current.

Klaus 4. ## Re: The simplest definition of VOLTAGE you can come up with

Hi,

In the dumbest terms possible? Voltage is the noun for electricity that comes from the person who discovered it, called Volta. 5. ## Re: The simplest definition of VOLTAGE you can come up with Originally Posted by gubavac111 I've measured it thousands of times, talked about it hundreds of times, but never reaaaaally understood it.

All those definitions seemed so complex, as if they are trying to make the voltage seem so mysterious.

So, after a little bit of thinking, I think the simplest definition of voltage I could come up with would be:

"Voltage is the difference in the amount of electrons between 2 (or more) points."

What do you think? First of all, am I mistaken? If I am, how so?

How would you explain voltage in the dumbest terms possible?
sorry gubavac, "Voltage is the difference in the amount of electrons between 2 (or more) points." is
a statement about static electricity, not voltage

sorry, again, gubavac, the dumbest terms possible does no one any good

i prefer this:
voltage is a measure of the difference in electrical potential energy between two locations

consider a bowling ball analogy:
if you drop it onto your foot from 2 cm, it hurts
if you drop it onto your foot from 2 m, it will likely break a few bones.
the difference is due to the difference in gravitational potential energy of the two situations

now, divide the gravitational potential energy of the bowling ball by the mass of the bowling ball
that is gravitational potential, a measure of the gravitational potential energy between two locations
the two locations are your foot, and the place the bowling ball is dropped from

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6. ## Re: The simplest definition of VOLTAGE you can come up with Originally Posted by gubavac111 I've measured it thousands of times, talked about it hundreds of times, but never reaaaaally understood it.

All those definitions seemed so complex, as if they are trying to make the voltage seem so mysterious.

So, after a little bit of thinking, I think the simplest definition of voltage I could come up with would be:

"Voltage is the difference in the amount of electrons between 2 (or more) points."

What do you think? First of all, am I mistaken? If I am, how so?

How would you explain voltage in the dumbest terms possible?
Look at the units of voltage, joules/coulomb. It is the energy density of the charge. It takes energy to bring two charge carriers from infinity together to within a certain distance from each other. It takes more energy to bring them closer to each other. Even more energy to bring more charge carriers carriers together. Get the idea? Divide the energy in joules by the number of charge carriers in coulombs to get volts, which is the energy density per charge. Now, the same polarity charge carries at one point of a conductor don't like each other, so they are going to go where the energy density is less. In other words, where the voltage is less. So, if the conduction path exists, a current will exist to the lower voltage. So, to iterate, voltage is the energy density of the charge carriers (usually electrons). If the charge carriers are highly concentrated, the voltage will be high. I hope that explains it.

Ratch 7. ## Re: The simplest definition of VOLTAGE you can come up with

@Ratch
"If the charge carriers are highly concentrated, the voltage will be high. I hope that explains it."

i don't think that's right

given a simple loop with a few resistors, the current is the same everywhere
there is no place where the charges are more concentrated, but there are certainly places where the voltage is higher

as you said, voltage = joules / coulomb, is the energy density per charge
more energy (more voltage) doesn't mean more charge, it means more energy per charge or each charge has more energy •

8. ## Re: The simplest definition of VOLTAGE you can come up with Originally Posted by wwfeldman @Ratch
"If the charge carriers are highly concentrated, the voltage will be high. I hope that explains it."

i don't think that's right

given a simple loop with a few resistors, the current is the same everywhere
there is no place where the charges are more concentrated, but there are certainly places where the voltage is higher
Of course. In a current loop, the charges are distributed evenly, but the energy is not. Therefore, the voltages are different along the points of the conduction path.

as you said, voltage = joules / coulomb, is the energy density per charge
more energy (more voltage) doesn't mean more charge, it means more energy per charge or each charge has more energy
I never said more energy means more charge.

Ratch

1 members found this post helpful. 9. ## Re: The simplest definition of VOLTAGE you can come up with

I don't know about definition but the best analogy in my mind is pressure or force. 10. ## Re: The simplest definition of VOLTAGE you can come up with Originally Posted by asdf44 I don't know about definition but the best analogy in my mind is pressure or force.
Do mechanical or hydraulic engineers study electrical analogs when they learn the units of their craft? If not, then why do electrical science engineers sometimes learn about their working units by equating and confusing them with foreign analogs. Voltage is not pressure or force, and amperage is not volume. Don't complicate your thinking by running it on two parallel tracks. Keep your head screwed on tight.

Ratch 11. ## Re: The simplest definition of VOLTAGE you can come up with Originally Posted by Ratch Do mechanical or hydraulic engineers study electrical analogs when they learn the units of their craft? If not, then why do electrical science engineers sometimes learn about their working units by equating and confusing them with foreign analogs. Voltage is not pressure or force, and amperage is not volume. Don't complicate your thinking by running it on two parallel tracks. Keep your head screwed on tight.
Ratch
Yes - I agree with Ratch. I do not like such "analogies" at all because - in many, if not in most cases - they do not improve the understanding. 12. ## Re: The simplest definition of VOLTAGE you can come up with

What do you think? First of all, am I mistaken? If I am, how so?
Seriously wrong.

Voltage is a potential. It has nothing to with electrons; it has to do only with the electric field.

The potential is defined and measured in terms of work. Hence voltage has the dimensions of energy. Electric field has the dimensions of force (it is a force field).

It is more like temperature. A bucket of water has more heat compared to a burning matchstick. But a burning matchstick has far higher temperature compared to the bucket of water.

But heat always flows from high temp to low temp. So a burning matchstick can transfer heat to a bucket of water (and not the other way).

In real life, potential difference is the most important thing between two bodies: it determines the direction of flow of charge. Just like a temp difference. Potential is considered zero only at infinity (where there are no electric fields).

Potential is not a force (electric field is) and is a scaler quantity (forget about the vector potential for the time being). 13. ## Re: The simplest definition of VOLTAGE you can come up with Originally Posted by c_mitra Seriously wrong.

Voltage is a potential. It has nothing to with electrons; it has to do only with the electric field.
It has to do with both the electric field and the number of charge carriers. It takes/gives more voltage to move several charge carriers to/from an electric field difference than it does for a single charge carrier.

The potential is defined and measured in terms of work. Hence voltage has the dimensions of energy. Electric field has the dimensions of force (it is a force field).
Voltage is the electrical energy density of the charge(joules/coulomb). It is a static density field with no direction. An electric field is a vector field of force with direction.

It is more like temperature. A bucket of water has more heat compared to a burning matchstick. But a burning matchstick has far higher temperature compared to the bucket of water.

But heat always flows from high temp to low temp. So a burning matchstick can transfer heat to a bucket of water (and not the other way).
You are correct because you are quoting the second law of thermodynamics.

In real life, potential difference is the most important thing between two bodies: it determines the direction of flow of charge. Just like a temp difference. Potential is considered zero only at infinity (where there are no electric fields).
Potential can be considered zero anywhere, but infinity is usually selected.

Potential is not a force (electric field is) and is a scaler quantity (forget about the vector potential for the time being).
Yes, energy whether kinetic or potential is a scalar, not a vector quantity. Don't forget that an electric field has a direction besides a force.

Ratch 14. ## Re: The simplest definition of VOLTAGE you can come up with

It has to do with both the electric field and the number of charge carriers. It takes/gives more voltage to move several charge carriers to/from an electric field difference than it does for a single charge carrier.
Wrong.

Every electric field is associated with a potential field (V=integral of Fdx over x to infinity). It has nothing to do with the number of charge carriers (by the way, what is a charge carrier???). Consider a positive charge (positioned at origin) and it will have a field all around (directed radially) and every point will be associated with a potential.

You are correct because you are quoting the second law of thermodynamics.
You need to brush up your thermodynamics. It is not difficult.

Potential can be considered zero anywhere, but infinity is usually selected.
That depends on the integration constant; for local effects only potential difference is meaningful. Absolute potential can be considered zero only in a field free space.

By the way, potential is not a density (you are confused because of the work/charge notion) function. Potential can be defined at any given point.

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15. ## Re: The simplest definition of VOLTAGE you can come up with Originally Posted by c_mitra Wrong.

Every electric field is associated with a potential field (V=integral of Fdx over x to infinity). It has nothing to do with the number of charge carriers (by the way, what is a charge carrier???). Consider a positive charge (positioned at origin) and it will have a field all around (directed radially) and every point will be associated with a potential.
The electric field increase is a measure of the difference in the energy density of the field. Therefore, if it measures X volts to move 1 coulomb of charge to a new position against a field, it will measure 2 X volts to move 2 coulombs to the new position. A charge carrier is a unit mass that carries a charge like a electron, hole, or proton.

You need to brush up your thermodynamics. It is not difficult.
Correct, it is not difficult. I stand by what I said about the second law.

That depends on the integration constant; for local effects only potential difference is meaningful. Absolute potential can be considered zero only in a field free space.
There is no absolute potential. Voltage is always measured relative to some point.

By the way, potential is not a density (you are confused because of the work/charge notion) function. Potential can be defined at any given point.
If not density, the what is it? Look at the voltage units (joules/coulomb). Density can be defined at any point, right? Surely potential is not energy. You can run a comb through you hair and get several thousand volts on it. But, with so few coulombs on the comb the energy accumulated is minuscule.

Ratch

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