Charge of an electron in Coulombs?

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Discussion Overview

The discussion revolves around the charge of an electron in Coulombs and its implications for understanding electric current. Participants explore the relationship between charge, current, and the sign convention used in these contexts, along with examples from textbooks.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant questions whether the charge of an electron is correctly stated as -1.602 176 565(35) • 10^-19 C, leading to confusion about negative currents.
  • Another participant explains that current is defined as flowing in the direction of positive charge carriers, which clarifies why the negative sign does not affect the direction of current flow.
  • There is a query about calculating the number of electrons corresponding to a charge of 18 C, which raises the issue of negative numbers of electrons.
  • A participant points out that if an object is missing electrons, it will have a positive charge, suggesting a conceptual understanding of charge neutrality.
  • Participants discuss a textbook example involving a 5 amp current and how to calculate the total charge, emphasizing the importance of using the magnitude of the electron charge.
  • There is a clarification that the Coulomb can be viewed as a unit for the magnitude of charge, which relates to the negative charge of the electron.

Areas of Agreement / Disagreement

Participants generally agree on the definition of current and the charge of an electron, but there are differing views on how to interpret negative charges and their implications for calculations involving electrons.

Contextual Notes

Some assumptions about charge neutrality and the historical context of charge carrier definitions are present but not fully explored. The discussion does not resolve the conceptual challenges posed by negative charges in calculations.

Who May Find This Useful

This discussion may be useful for students and individuals interested in understanding electric charge, current flow, and the implications of charge sign conventions in physics.

mosad655
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Is it correct that the charge of an electron in Coulombs is

- 1,602 176 565(35) • 10-19 C ?

By inserting this in the formula for current I = Q / t, that would make the current a negative number. I don't reckon having read about negative currents though. So what's the explanation for how the negative sign dissappears and currents end up always being positive?
 
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mosad655 said:
So what's the explanation for how the negative sign dissappears and currents end up always being positive?
Current is usually defined as flowing in the direction of positive charge carriers. (Historically, it wasn't anticipated that the charge carriers in a wire, for instance, were actually negatively charged.) So if electrons move to the right, the current is defined as moving to the left.
 
but is it correct that the charge of an electron in Coulombs is - 1,602 176 565(35) • 10^-19 ?
 
mosad655 said:
but is it correct that the charge of an electron in Coulombs is - 1,602 176 565(35) • 10^-19 ?
Sure.
 
so let's say.. 18 C would be then be 18 / (- 1,602 176 565(35) • 10^(-19)) electrons? That's a negative number, how is it possible to have a negative number of electons?
 
mosad655 said:
so let's say.. 18 C would be then be 18 / (- 1,602 176 565(35) • 10^(-19)) electrons? That's a negative number, how is it possible to have a negative number of electons?
What's 18 C? Obviously not the charge on a bunch of electrons. Realize that if something ordinarily neutral is missing a number of electrons, that it will have a positive charge.

What problem are you trying to solve?
 
In the textbook that I have, it comes with this example:

A 5 amp current flows for an hour. The total charge that passes by in such case, is Q = I • t = 5 A • 3600 s = 18000 C or 18000 Coulombs. Now how many electrons is that?
 
mosad655 said:
In the textbook that I have, it comes with this example:

A 5 amp current flows for an hour. The total charge that passes by in such case, is Q = I • t = 5 A • 3600 s = 18000 C or 18000 Coulombs. Now how many electrons is that?
Just divide by the magnitude of the electron charge. Don't get hung up with signs.
 
So coulomb is not the unit for charge, but the unit for the magnitude of charge?
 
  • #10
mosad655 said:
So coulomb is not the unit for charge, but the unit for the magnitude of charge?
You can think of it that way. That's why the charge on the electron is a negative number of Coulombs.
 

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