Voltage between two different charges

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Discussion Overview

The discussion centers on the calculation of voltage between two different charges in the context of static electricity and capacitors. Participants explore how to determine voltage when dealing with two pieces of metal that possess different charges, considering factors such as capacitance, distance, and charge density.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Veniamin proposes that voltage is calculated as Charge divided by Capacitance, questioning how this applies when two different charges are involved.
  • One participant suggests using the formula V = -∫ E dl to calculate voltage, indicating the need to determine the electric field of the charged capacitor.
  • Another participant echoes the previous suggestion about using the integral of the electric field to find voltage, expressing confusion about how to define the electric field when different charge densities are present.
  • There is a mention that charge density is proportional to charge, but uncertainty remains regarding the calculation of voltage based on two different charges.
  • One participant notes that the electric field may depend on the type and shape of the capacitor, indicating variability in the situation.

Areas of Agreement / Disagreement

Participants express uncertainty and seek clarification on how to approach the problem, indicating that no consensus has been reached regarding the calculation of voltage between two different charges.

Contextual Notes

Participants highlight the complexity of the problem, particularly regarding the definitions and calculations of electric field and charge density in the context of different charges, which remain unresolved.

LiteHacker
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Voltage = Charge / Capacitance.

This assumes that the capacitor has +Q charge on one side and -Q charge on the other side.

What if you have two different charges?

I mean in terms of static electricity, if you have a piece of metal with one charge, and another piece of metal with another charge, the capacitance between them depends on their distance from each other and their volume... But they have two different charges.

How do you find the voltage?

Thank you,
Veniamin
 
Last edited:
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I think by using the formula V=-\int \vec E d \vec l so you'd have to calculate the electric field of the charged capacitor.
 
fluidistic said:
I think by using the formula V=-\int \vec E d \vec l so you'd have to calculate the electric field of the charged capacitor.

Indeed, after spending a while on http://en.wikipedia.org/wiki/Capacitor#Parallel_plate_model", I found that E = +- charge density / some constant ..
It goes on taking the integral of E * something = Voltage

But, I don't understand what E equals if you have two different charge densities.

Does anybody?

Note that it seems safe to assume that charge is proportional charge density, so we are still trying to figure out the original problem:
What voltage do you get based on two different charges?
 
Last edited by a moderator:
LiteHacker said:
Indeed, after spending a while on http://en.wikipedia.org/wiki/Capacitor#Parallel_plate_model", I found that E = +- charge density / some constant ..
It goes on taking the integral of E * something = Voltage

But, I don't understand what E equals if you have two different charge densities.

Does anybody?

Note that it seems safe to assume that charge is proportional charge density, so we are still trying to figure out the original problem:
What voltage do you get based on two different charges?
You'd have to find out \vec E, I believe but not 100% sure. This value may depends on the type of capacitor and its shape.
I'll wait someone else to enlighten us.
 
Last edited by a moderator:

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