Concept of Voltage

  • #1

Main Question or Discussion Point

Hi, I have been having trouble understanding this: Potential difference(Voltage) increases when charged particles travel against electric field lines.

My question is why does the charge of the particle not affect Voltage? Why does an electron and a proton traveling in the same direction cause the same Voltage?
 

Answers and Replies

  • #2
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They don't. Their effects are opposite as you would expect from opposite charges.
 
  • #3
They don't. Their effects are opposite as you would expect from opposite charges.
Maybe I'm asking this wrong. I want to know why there is higher potential against electric field lines and lower potential with electric field lines.
 
  • #4
867
60
Visualize the electric field a different way and I think your understanding will clear up.

Electric field is nothing more then the tendency of like electrostatic charges to repel one another and unlike charges to attract. If you have a positively charged object and a negatively charged object the excess protons in the positively charged object will repel each other. Electrons in the negatively charged object will also try to repel each other. Electrons in the negatively charged object will be attracted to protons in the positively charged object and vice verse. This attraction is measured in volts. This attraction (voltage) causes electrons to move from the negative object to the positive object, it is also possible for protons to move from the positive object to the negative object. That would not happen very much in a solid medium but in a liquid, gaseous, or plasma medium it certainly can. The movement of the charges is called current and measured in amperes.

The idea that electric potential can exist independent of charged particles comes from the idea that voltage can be induced my a magnetic field in an otherwise neutrally charged object. This idea becomes unnecessary if magnetic fields are understood as nothing more then the result of electric fields that are in motion with respect to one another. Here is a link that explains this concept very well...

http://physics.weber.edu/schroeder/mrr/MRRtalk.html

So with this bit of understanding magnetism is out the window and everything is understood as the interaction of charged particles. To my mind this is the simplest possible explanation. Everything is nice and tidy and self consistent. That's how I like it. :-)
 
  • #5
Andrew Mason
Science Advisor
Homework Helper
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Maybe I'm asking this wrong. I want to know why there is higher potential against electric field lines and lower potential with electric field lines.
When you run up a hill (ie. against the gravitational field) do you increase or decrease your gravitational potential?

AM
 
  • #6
When you run up a hill (ie. against the gravitational field) do you increase or decrease your gravitational potential?

AM
increase
 
  • #7
Visualize the electric field a different way and I think your understanding will clear up.

Electric field is nothing more then the tendency of like electrostatic charges to repel one another and unlike charges to attract. If you have a positively charged object and a negatively charged object the excess protons in the positively charged object will repel each other. Electrons in the negatively charged object will also try to repel each other. Electrons in the negatively charged object will be attracted to protons in the positively charged object and vice verse. This attraction is measured in volts. This attraction (voltage) causes electrons to move from the negative object to the positive object, it is also possible for protons to move from the positive object to the negative object. That would not happen very much in a solid medium but in a liquid, gaseous, or plasma medium it certainly can. The movement of the charges is called current and measured in amperes.

The idea that electric potential can exist independent of charged particles comes from the idea that voltage can be induced my a magnetic field in an otherwise neutrally charged object. This idea becomes unnecessary if magnetic fields are understood as nothing more then the result of electric fields that are in motion with respect to one another. Here is a link that explains this concept very well...

http://physics.weber.edu/schroeder/mrr/MRRtalk.html

So with this bit of understanding magnetism is out the window and everything is understood as the interaction of charged particles. To my mind this is the simplest possible explanation. Everything is nice and tidy and self consistent. That's how I like it. :-)
This helps, thanks!
 
  • #8
Andrew Mason
Science Advisor
Homework Helper
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increase
Similarly, when you push a charge against the electric force, you increase its potential. The only difference is that gravity is always attractive whereas an electric force can be attractive or repulsive. An electric field, by convention, points in the direction that a free positive charge will move. So a negative charge naturally moves against the direction of the electric field (we could have established a different convention but it was set before anyone understood what charge was). So for a negative charge you have to do work when moving in the direction of electric field (ie. against the force on the negative charge) in order to increase its potential.

AM
 
  • #9
1,161
82
Visualize the electric field a different way and I think your understanding will clear up.

Electric field is nothing more then the tendency of like electrostatic charges to repel one another and unlike charges to attract. If you have a positively charged object and a negatively charged object the excess protons in the positively charged object will repel each other. Electrons in the negatively charged object will also try to repel each other. Electrons in the negatively charged object will be attracted to protons in the positively charged object and vice verse. This attraction is measured in volts. This attraction (voltage) causes electrons to move from the negative object to the positive object, it is also possible for protons to move from the positive object to the negative object. That would not happen very much in a solid medium but in a liquid, gaseous, or plasma medium it certainly can. The movement of the charges is called current and measured in amperes.

The idea that electric potential can exist independent of charged particles comes from the idea that voltage can be induced my a magnetic field in an otherwise neutrally charged object. This idea becomes unnecessary if magnetic fields are understood as nothing more then the result of electric fields that are in motion with respect to one another. Here is a link that explains this concept very well...

http://physics.weber.edu/schroeder/mrr/MRRtalk.html

So with this bit of understanding magnetism is out the window and everything is understood as the interaction of charged particles. To my mind this is the simplest possible explanation. Everything is nice and tidy and self consistent. That's how I like it. :-)
I don't think that is what modern physics says. Magnetic fields are due to charges in motion. According to A Einstein in his 1905 paper "On The Electrodynamics Of Moving Bodies", between electric & magnetic fields, that neither is the seat. The two are interrelated & it is safe to say that charges give rise to both E & H fields. But to say that magnetic is just a moving version of electric, goes counter to relativity & QED. Both E & H (or "B" if you prefer) are a result of charge interaction. Static charges result in E, whereas moving charges produce H. Different reference frames see differing proportions of E & H, but the two are inclusive, neither being more fundamental.

I don't wish to notpick, but Einstein's 1905 paper still stands in the science community today. No discovery has been made to void said position. E & H are 2 sides of the same coin.

Claude
 
  • #10
867
60
I don't think that is what modern physics says. Magnetic fields are due to charges in motion. According to A Einstein in his 1905 paper "On The Electrodynamics Of Moving Bodies", between electric & magnetic fields, that neither is the seat. The two are interrelated & it is safe to say that charges give rise to both E & H fields. But to say that magnetic is just a moving version of electric, goes counter to relativity & QED. Both E & H (or "B" if you prefer) are a result of charge interaction. Static charges result in E, whereas moving charges produce H. Different reference frames see differing proportions of E & H, but the two are inclusive, neither being more fundamental.

I don't wish to notpick, but Einstein's 1905 paper still stands in the science community today. No discovery has been made to void said position. E & H are 2 sides of the same coin.

Claude
I'm not disputing that. Any mathematical model that makes correct predictions can be thought of as correct. Einsteins model meets that criteria and so it is a good model. Modeling everything as E fields as outlined in the link I provided makes identical predictions and so is an equally valid model. Whichever model you find more intuitive or easier to use is the one you should use.
 

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