Why is the terminology in electrical engineering so redundant and confusing?

[NascentOxygen]

Why doesn't my residential electricity provider just bill me in coulombs (C) each month. Why do we have such ridiculous concoctions like kWh?

You have a good point, especially in light of the fact that your electricity supply voltage is held reasonably constant. But by billing you for kWH instead of coulombs it's saving you money, so that's probably a good enough reason. Right? Money talks!

You see, not every coulomb delivers you the same amount of energy, some coulombs might do only 65% of the work that others do. But if you were to tell the power authority that you are happy to pay full price for each coulomb, regardless, then if you are a big customer I'm sure they would fall over themselves in their haste to have you sign such for such a deal. By metering in kWH they are charging you for the actual energy delivered, meaning those coulombs working at less than full effort are automatically costed at a lower pro rata charge. Few customers take issue with that.

 

[sophiecentaur]

You have a good point, especially in light of the fact that your electricity supply voltage is held reasonably constant. But by billing you for kWH instead of coulombs it's saving you money, so that's probably a good enough reason. Right? Money talks!

You see, not every coulomb delivers you the same amount of energy, some coulombs might do only 65% of the work that others do. But if you were to tell the power authority that you are happy to pay full price for each coulomb, regardless, then if you are a big customer then I'm sure they would fall over themselves in their haste to have you sign such for such a deal. By metering in kWH they are charging you for the actual energy delivered, meaning those coulombs working at less than full effort are automatically costed at a lower pro rata charge.

The point is that you are buying Energy, because that's what heats your house and works your washing machine. Coulombs do not constitute Energy on their own, any more than the links on a bicycle chain provide motive power. TrueRock is trying to impose his own private version of Electrical Units in this and it just doesn't work. There is absolutely no direct correspondence between Coulombs and Joules. The Volts (Joules per Coulomb) must be stated.

 

[sophiecentaur]

. . . . . and, of course, with AC, there is no net transfer of Coulombs - so you don't actually get any!

 

[True Rock]

Well... after spending many hours reading various opinions on the topic... I am bemused to admit once again Wikipedia provided the explanation that provided the most help for my purpose. I am repeatedly astonished that this one source of information keeps popping up as the place I find answers to my questions.

Etymology of electricity

In physics the term quantity of electricity refers to the quantity of electric charge.
It is designated by the letter Q and in the SI system is measured in derived units called coulombs.

Charge, in the electrical sense, was first used in 1767.

The term quantity of electricity was once common in scientific publications.
It appears frequently in the writings of Franklin, Faraday, Maxwell, Millikan, and J. J. Thomson, and was even occasionally used by Einstein.
However, over the last hundred years the term "electricity" has been used by electric utility companies and the general public in a non-scientific way.

Today the vast majority of publications no longer refer to electricity as meaning electric charge.
Instead they speak of electricity as electromagnetic energy.
The definition has drifted even further, and many authors now use the word "electricity" to mean electric current (amperes), energy flow (watts), electrical potential (volts), or electric force.
Others refer to any electrical phenomena as kinds of electricity.

These multiple definitions are probably the reason that Quantity of Electricity has fallen into disfavor among scientists.
Physics textbooks no longer define Quantity of Electricity or Flow of Electricity.
Quantity of electricity is now regarded as an archaic usage, and it has slowly been replaced by the terms charge of electricity, then quantity of electric charge, and today simply charge.
Since the term electricity has increasingly become corrupted by contradictions and unscientific definitions, today's experts instead use the term charge to remove any possible confusion.

 

[russ_watters]

You have a good point, especially in light of the fact that your electricity supply voltage is held reasonably constant.

"Held constant", yes, but most customers use multiple voltages simultaneously. I use both 120 and 240V. Commercial services go as high as 13.2kV, three phase, so different users get vastly different amounts of energy for the same coulombs.

And I assume the rest of your post was about power factor. Another good reason why coulombs alone isn't enough.

 

[Drakkith]

Well... after spending many hours reading various opinions on the topic... I am bemused to admit once again Wikipedia provided the explanation that provided the most help for my purpose. I am repeatedly astonished that this one source of information keeps popping up as the place I find answers to my questions.

Etymology of electricity

In physics the term quantity of electricity refers to the quantity of electric charge.
It is designated by the letter Q and in the SI system is measured in derived units called coulombs.

Charge, in the electrical sense, was first used in 1767.

The term quantity of electricity was once common in scientific publications.
It appears frequently in the writings of Franklin, Faraday, Maxwell, Millikan, and J. J. Thomson, and was even occasionally used by Einstein.
However, over the last hundred years the term "electricity" has been used by electric utility companies and the general public in a non-scientific way.

Today the vast majority of publications no longer refer to electricity as meaning electric charge.
Instead they speak of electricity as electromagnetic energy.
The definition has drifted even further, and many authors now use the word "electricity" to mean electric current (amperes), energy flow (watts), electrical potential (volts), or electric force.
Others refer to any electrical phenomena as kinds of electricity.

These multiple definitions are probably the reason that Quantity of Electricity has fallen into disfavor among scientists.
Physics textbooks no longer define Quantity of Electricity or Flow of Electricity.
Quantity of electricity is now regarded as an archaic usage, and it has slowly been replaced by the terms charge of electricity, then quantity of electric charge, and today simply charge.
Since the term electricity has increasingly become corrupted by contradictions and unscientific definitions, today's experts instead use the term charge to remove any possible confusion.

Honestly I don't see what this has to do with the topic at hand. No one here, including yourself, ever talked about the term "electricity". All wikipedia is doing is saying that "electricity" is an ambiguous term nowadays. It still doesn't explain the relationship between all the terms you were asking about nor why they are defined as they are.

 

[M Quack]

Chapters 1 -- 18 of the famous Feynman lectures should provide you with a reasonable overview of "electricity" and a bit of the math that goes along with it. Coming from a Nobel prize winner you can probably trust his opinion on undergraduate material.

http://www.feynmanlectures.caltech.edu/II_toc.html

After that there is always Jackson's book, but that is not exactly bedside reading.

https://www.amazon.com/dp/047130932X/?tag=pfamazon01-20

 

[sophiecentaur]

In physics the term quantity of electricity refers to the quantity of electric charge.

Not on any regular basis. The term is not defined anywhere with serious authority that I know. Wiki may be ones friend when first approaching a topic but, as any Tom Dick or Harry can contribute to or modify it, it can never be taken as the ultimate arbiter of anything.
But why has it taken 40 Posts to get this far (i.e. nowhere)?

 

[davenn]

. . . . . and, of course, with AC, there is no net transfer of Coulombs - so you don't actually get any!

which is what I said many posts before yours ;)

The thread should have stayed locked ... its gotten nowhere as you stated :)
its sad that even after all this discussion, we still have a person who is completely unwilling to attempt to listen to and learn the basics :(

Dave

 

[Dale]

Re closed pending moderation

EDIT: the thread will remain closed this time.