Why does everything electrical we see give its voltage?

[Dadface]

Yes there is a potential with respect to other charged objects particles etc.The evidence seems to show that the electric force spreads to infinity being inversely proportional to separation squared.

 

[barton]

There is. I was more curious about how voltage drops occur in the confines of an electric circuit. As long as you have the presence of nearby charges, the presence of nearby time-varying magnetic fields, or the presence of nearby moving magnetic fields, you will have electric fields set up in your region of space. Depending on what you choose as your reference point (0V), and the shape and strength of the resulting electric fields, you will be able to measure differences in potential at various points in space.

 

[Phrak]

There is. I was more curious about how voltage drops occur in the confines of an electric circuit. As long as you have the presence of nearby charges, the presence of nearby time-varying magnetic fields, or the presence of nearby moving magnetic fields, you will have electric fields set up in your region of space. Depending on what you choose as your reference point (0V), and the shape and strength of the resulting electric fields, you will be able to measure differences in potential at various points in space.

A good point. Are transformers included as elementry circuit elements? So potenial difference--not completely path independent--depends on how it's measured even where the electric fields are time independent. Every turn around a solenoid obtains a different potential.

 

[nuby]

This might be too simple... But, why not look at a unit of charge as just a quantity of electrons or mass, and that's it. Then voltage could just be the electrostatic force that moves electrons through circuits at a specific velocity (or vibration) .. . On one end of a circuit you have a quantity of extra electrons (-), and then on the other end you have the 'potential' ((+) holes) waiting to be filled, which suck electrons through the circuit (performing work).

 

[Dadface]

Electrons carry charge and voltage is related to force.It may help to think of it in terms of an energy circuit.In the power supply the charged particles pick up energy.With a battery chemical energy is changed to electrical energy with a generator kinetic energy is changed to electrical energy and so on.The emf[voltage] of the supply is a .measure of how many joules of energy are given to each coulomb of charge that passes through it[the charge carried by a single electron is about 1.6 times ten to the power of minus nineteen coulombs].In the external circuit the energy picked up by the electron is converted to other forms of energy.The actual energy output depends on what the circuit is for example if the circuit was nothing more than a connecting wire carrying a steady dc current then the energy output would be heat.The voltage across the external circuit is a measure of how many joules of energy are converted by each coulomb of charge that passes through.In summary the power supply is a sort of pump which gives the charged particles energy and pumps them round the circuit where the energy is released in a different form

 

[Denton]

You've discovered a super hoax actually, but keep it quiet because there's a whole big industry living off its spread. You don't need two outlets on a power outlet, that's just to increase its price. One single outlet is quite sufficient, as long as you do a rain dance when you switch on your appliance of choice.

BTW, yes, I'm making (gently) some fun of your statements

No youre right, there is no reason to have all these excess cables for AC when one power cable suffices. The other end is simply connected to Earth to complete the loop.

 

[cabraham]

No youre right, there is no reason to have all these excess cables for AC when one power cable suffices. The other end is simply connected to Earth to complete the loop.

Using the Earth to complete the loop is not done for good reason. Soil, especially dry, is not a very good conductor. Two conductors are used for good reason, low resistance, and also low inductance.

I think the poster you responded to may not have been discussing 2 wires, but rather 2 outlets per duplex receptacle. One would work, but two is more convenient. BR (best regards).

Claude

 

[Dadface]

Claude is right.We don't have an easy way to theoretically quantify the power losses in an Earth conductor but rest assured that the losses are huge.

 

[Red_CCF]

I have a follow up question on this topic. When you have trillions of electrons flowing through the same circuit, does each electron interfere with the force of the voltage that is used to push them? Like would the electrons in the middle of the circuit feel less force than electrons close to the ends?

If so if this significant or is the difference negligible. Thanks

 

[Xezlec]

I have a follow up question on this topic. When you have trillions of electrons flowing through the same circuit, does each electron interfere with the force of the voltage that is used to push them? Like would the electrons in the middle of the circuit feel less force than electrons close to the ends?

If so if this significant or is the difference negligible. Thanks

I don't think you're thinking about this clearly. It's just like water flowing through a pipe. Voltage is like pressure difference between two points in the pipe. Resistance is like the narrowness of the pipe. Current is like the rate of flow of water. You can think of electrons as being the water molecules.

You asked about how much force electrons feel in different places. I'll answer that, but I'm not sure that's what you meant to ask. Force is the gradient of potential energy, which just means that the force felt by the electrons at any given point is just how fast the voltage is changing (as a function of position) at that point. Going back to the water analogy, this is the same as saying the force felt by the water at a point in the pipe is proportional to how fast the water pressure is dropping off at that point.

Now, if we are talking about a single straight path with no branches, we know that the current (rate of flow) must be the same through the whole path. Otherwise, there would have to be water/electrons accumulating somewhere or something, which doesn't happen in this simple of a model. Since the change in pressure (voltage) across some piece of the path equals the current (rate of flow) through it times the resistance of that section of pipe, and since the current is the same all the way through it, we can see that the change in pressure is just proportional to the resistance at any point in the pipe. Therefore, the force an electron feels when it's somewhere along a simple straight path is proportional to the resistance of the path at that point.

As usual in physics, there's an easier way to see all of this: the current is the same everywhere, but the resistance (force pushing back) is stronger in some places, so to keep the electrons flowing at the same rate everywhere, they must be feeling more forward force in the places with higher resistance, in order to fight the resistance and win.

The water analogy is a very very good analogy. Use it and all will become clear.

This probably doesn't really help you with what you're thinking about, but I think I'm going to need you to try and ask a more precise question in order to go further down this line of questioning, if that's ok.

 

[Red_CCF]

You asked about how much force electrons feel in different places. I'll answer that, but I'm not sure that's what you meant to ask. Force is the gradient of potential energy, which just means that the force felt by the electrons at any given point is just how fast the voltage is changing (as a function of position) at that point. Going back to the water analogy, this is the same as saying the force felt by the water at a point in the pipe is proportional to how fast the water pressure is dropping off at that point.

Thanks for the reply.

Yea I meant to ask about the force that electrons feel at different places on a circuit. I didn't really understand what you meant when you said that force is a gradient of potential energy. Is it a gradient on a graph? If so what type of graph? I'm just wondering whether force of the voltage that pushes the electrons through are changing (even if it's really small) as the electrons moves away from the terminals on a voltage source. If this does happen, is it other electrons near the terminals that interfere with the force being felt by electrons in the middle of the circuit?

Thanks for the help

 

[Xezlec]

Yea I meant to ask about the force that electrons feel at different places on a circuit.

OK, well then good. That's what I answered.

I didn't really understand what you meant when you said that force is a gradient of potential energy.

"Gradient" is vector calculus terminology. If you aren't familiar with that subject, then ignore that sentence. That's why I explained it so many different ways. Take your pick. The water analogy is the simplest and best explanation, I think.

I'm just wondering whether force of the voltage that pushes the electrons through are changing (even if it's really small) as the electrons moves away from the terminals on a voltage source.

My problem is that I feel like I answered that question completely, so I'm not sure why you're still wondering that. I'll say it again: the force an electron feels is proportional to the resistance of the path at that point, so the force changes wherever the resistance changes and the force stays the same wherever the resistance stays the same. I still feel like there has to be some part of your question I don't understand.

Well, we can both think about it, and maybe I'll come up with a clearer way to phrase it later.

 

[rcgldr]

Voltage is a potential, not a force. Imagine a infinitely large plate with some amount of charge per unit area. The electrical intensity is constant regardless of position. An absolute voltage could be defined as the the intensity x distance (height) from the plate. For some object in the field with charge q, voltage x q would be the electrical potential energy. The electrical force = inensity x charge, independent of distance from the plate (or voltage).

As an analogy, imagine an infinitely large plate with some amount of mass per unit area. The gravitational intensity is constant regardless of position. An absolute gravitational potential (no special name for this that I know of) could be defined as the the intensity x distance (height) from the plate. For some object in the field with mass m, gravitational_potential x m would be the gravitational potential energy. The gravitational force = inensity x mass, independent of distance from the plate (or gravitational potential).

 

[Red_CCF]

My problem is that I feel like I answered that question completely, so I'm not sure why you're still wondering that. I'll say it again: the force an electron feels is proportional to the resistance of the path at that point, so the force changes wherever the resistance changes and the force stays the same wherever the resistance stays the same. I still feel like there has to be some part of your question I don't understand.

Please forgive me if I'm a bit slow. I understand Ohm's law which is the basis of your point. But I'm trying to ask whether the electrons exert some sort of electrostatic force on each other which may change the magnitude of the force that that they feel.