Why isn't CHARGE a fundamental quantity rather than CURRENT?

In summary, there is a contradiction between the definition of a fundamental quantity (a quantity that can't be described in terms of another quantity) and the definition of electric current. It seems more likely that the fundamental quantity "electric current" should be replaced by the quantity "charge" and that the fundamental unit should be the coulomb.
  • #1
tan99
7
0
Almost all physics or engineering textbooks have a table of the SI units
that are based on six fundamental quantities. The one that is listed for
the quantity "electric current" is always "ampere". However, usually a few
pages past this fundamental table lies a definition of the ampere. 1 ampere
= 1 coulomb/second. This makes it sound more like a derived unit than a
fundamental unit. It seems more likely that the fundamental quantity
"electric current" should be replaced by the quantity "charge" and that the
fundamental unit should be the coulomb. While amperes can be broken down
into coulombs and seconds, the coulomb cannot be broken down (except to a
specific count of electrons or protons). Why does there seem to be some
contradiction between the definition of a fundamental quantity (a quantity
that can't be described in terms of another quantity) and the definition of
electric current? Why isn't charge along with the coulomb included in the
fundamental quantities table?
 
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  • #2
tan99 said:
Almost all physics or engineering textbooks have a table of the SI units
that are based on six fundamental quantities. The one that is listed for
the quantity "electric current" is always "ampere". However, usually a few
pages past this fundamental table lies a definition of the ampere. 1 ampere
= 1 coulomb/second. This makes it sound more like a derived unit than a
fundamental unit. It seems more likely that the fundamental quantity
"electric current" should be replaced by the quantity "charge" and that the
fundamental unit should be the coulomb. While amperes can be broken down
into coulombs and seconds, the coulomb cannot be broken down (except to a
specific count of electrons or protons). Why does there seem to be some
contradiction between the definition of a fundamental quantity (a quantity
that can't be described in terms of another quantity) and the definition of
electric current? Why isn't charge along with the coulomb included in the
fundamental quantities table?

It's true that 1 amp=1 Coulomb/second but of course 1 Coulomb=1 Amp second.I think the choice of what's considered to be more fundamental is guided largely by the experimental ease by which the unit can be established.The Ampere is defined with reference to the force between parallel current carrying wires which presents experimental difficulties to establish exactly but nevertheless is measurable to a high degree of accuracy.If we don't define the Coulomb with reference to the Ampere then how else should we define it?There must be ways but I'm assuming that the experiments needed to establish the unit are less accurate than the ones currently used.Anyway,like yourself I feel that the Coulomb is more fundamental than the Ampere.
 
  • #3
I wouldn't read very much into the fact that Amperes are an SI base unit, rather than Coulombs.
Heck, moles are an SI base unit, and it's not even a measure of anything.
 

1. Why is charge not considered a fundamental quantity?

Charge is not considered a fundamental quantity because it can be derived from other fundamental quantities such as current, voltage, and time. In fact, charge is defined as the product of current and time, or the integral of current over time.

2. What makes current a more fundamental quantity than charge?

Current is considered more fundamental because it represents the flow of charge, which is a more basic concept. Charge, on the other hand, is a property of matter and does not describe a physical flow.

3. Can charge be measured directly?

No, charge cannot be measured directly. It can only be measured indirectly by measuring the effects of charge, such as voltage or current.

4. What are the implications of charge not being a fundamental quantity?

The fact that charge is not a fundamental quantity has implications in the field of physics, where fundamental quantities are used to describe and explain natural phenomena. However, this does not diminish the importance of charge in understanding and analyzing electrical systems.

5. Is there a possibility that charge could be considered a fundamental quantity in the future?

It is unlikely that charge will be considered a fundamental quantity in the future, as it is already well-defined and understood in terms of other fundamental quantities. However, as our understanding of the universe continues to evolve, it is possible that new discoveries may lead to a reevaluation of what is considered fundamental.

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