Is there a way to break down the Culomb?

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Discussion Overview

The discussion explores the possibility of breaking down the unit of charge, the coulomb, into fundamental units of mass, length, and time. It touches on definitions and relationships between electrical units, particularly in the context of the SI system and alternative unit systems.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that most mechanical units can be expressed in terms of mass, length, and time, questioning if the coulomb can be similarly decomposed.
  • Another participant defines the ampere in terms of a force between conductors, indicating that a coulomb is equivalent to one ampere for one second.
  • A different viewpoint asserts that the ampere is an independent SI base unit and that the coulomb cannot be expressed using only mass, length, and time in the SI system.
  • One participant argues that electrical phenomena necessitate a fourth base quantity, implying that the coulomb is fundamental and cannot be resolved into the other three base units.
  • A later post mentions the equivalence of a coulomb to a specific number of elementary charges, suggesting implications for the definition of the kilogram as a derived unit.

Areas of Agreement / Disagreement

Participants express differing views on whether the coulomb can be broken down into mass, length, and time, with some asserting it cannot and others discussing its relationships with other units. The discussion remains unresolved regarding the fundamental nature of the coulomb in relation to other units.

Contextual Notes

Participants note that definitions of electrical units may vary between systems, such as SI and cgs, which could influence how charge is conceptualized and measured.

swraman
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The thread on mass and force made me think...
Most units in mechanics can be broken down into a combination of length, mass, and time.
eg. power = mass * distance * time^-2 * distance * time^-1 (force*velocity)

Is there any way to break the culomb down into mass, length, and time?
 
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Yes from the definition of the Ampere
"One ampere is defined to be the constant current which will produce an attractive force of 2×10^–7 Newton per metre of length between two straight, parallel conductors of infinite length and negligible circular cross section placed one metre apart in a vacuum"
And a coulomb is 1 Amp for 1 second.
 
Last edited:
However, the ampere is its own SI base unit, independent of the kilogram, metre, and second. In the SI system, the coulomb cannot be written in terms of these three base units.

However, in other unit systems, such as cgs (of which there is more than one type), units of charge are defined in terms of the other base units (centimetre, gram, second), but that is only due to the way they are defined, rather than anything physical.
 
The Coulomb cannot be resolved into mass, length, and/or time quantities. Electrical phenomena require the addition of a 4th base quantity to define them. The base electrical unit is the Coulomb, and all other electric/magnetic quantities are defined from the coulomb.

But, it is difficult to establish a measurement reference based on the Coulomb at this present time. If we define the amp as the current which results in a specific force between 2 conductors, it is precise and repeatable. So we define the amp per the above post, and the Coulomb is 1 amp * 1 sec. The Coulomb is actually more basic than the Amp, but it is easier to establish the Amp as the reference. I hope this helps. BR.

Claude
 
thanks
 
A coulomb is then equal to exactly 6.241 509 629 152 65×1018 elementary charges. Combined with the present definition of the ampere, this proposed definition would make the kilogram a derived unit.

http://en.wikipedia.org/wiki/Coulomb
 

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