Dimensional Units for Coulomb in SI

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    Coulomb Si Units
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Discussion Overview

The discussion revolves around the dimensional formula for the Coulomb in the SI system, specifically seeking a representation that does not involve amperes. Participants explore the relationships between Coulombs, Amperes, and the base SI units of mass (kg), length (m), and time (s), while addressing the implications of base units and derived units.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants inquire about a dimensional formula for the Coulomb that excludes amperes, expressing curiosity about potential relationships involving only m, kg, and s.
  • Others assert that one ampere is defined as one coulomb per second, emphasizing the challenge of expressing Coulombs without referencing Amperes.
  • A participant suggests that it is impossible to create a dimensionally consistent equation with only Coulombs on one side and only powers of m, kg, and s on the other side, citing the definition of base units.
  • Some argue that the Ampere is a base unit by definition, which implies it cannot be expressed in terms of other base units.
  • There are claims that the Coulomb is a fundamental unit, while others clarify that it is derived from the relationship between Amperes and seconds.
  • Participants discuss the historical context of unit definitions and the possibility of logical consistency within the SI system, questioning if base units could theoretically be defined in terms of one another.
  • Several analogies are presented to illustrate the independence of units, comparing the expression of charge to expressing mass in terms of length or time.

Areas of Agreement / Disagreement

Participants generally disagree on the possibility of expressing the Coulomb in terms of m, kg, and s without involving amperes. There is contention regarding the nature of base units and whether they can be defined in terms of other units, with some asserting that they cannot and others questioning the logical consistency of such definitions.

Contextual Notes

The discussion highlights the limitations of expressing derived units in terms of base units and the implications of unit definitions within the SI system. There is an acknowledgment that the definitions of units are based on consensus rather than fundamental physical principles.

  • #31
Yes, but the argument is more than two years old. PF discourages reviving old threads (a practice which is called necro-posting.)

You can, however, start your own thread, and refer to another thread, if you wish.
 
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  • #32
makrisj said:
Coulomb has dimensions of [M]^1/2 * [L]^3/2 * [T]^-1
No, it doesn't. See the official BIPM page: http://www.bipm.org/en/measurement-units/base-units.html
SteamKing said:
Yes, but the argument is more than two years old. PF discourages reviving old threads (a practice which is called necro-posting.)

You can, however, start your own thread, and refer to another thread, if you wish.
Yes. Thread closed.
 

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