# The evolution of the ampere

Discussion in 'Amp Central Station' started by Junior Little, Jun 12, 2019.

1. ### Junior LittleTele-Meister

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I dunno...thought it might be of interest.

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2. ### Digital LarryTele-Afflicted

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3. ### ObsessedDoctor of TeleocityAd Free Member

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Damn that Kelvin.

4. ### RodeoTexPoster Extraordinaire

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Isn't it really just a measure of how much work a circuit is doing?
If not I've built a whole career on a misunderstanding.

Now that Kelvin guy from my chemistry class years ago is starting to act up again with the edvent LED bulbs. THAT guy is the real problem.

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5. ### Torren61Tele-Afflicted

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No. I like to think about it this way: You have to use your imagination. You have a balloon. Blow it up with air and lay it on its side but don’t let out the air. Now, put a straw in the neck of the balloon but still keep the air in there. Put a pinwheel where the air is going to escape.

Ok. NOW let’s let the air escape through the straw and blow on the pinwheel. The air in the balloon is voltage. Pressure. The bigger the balloon and the more air you fill into the balloon, the more pressure (voltage).

The straw is resistance or Ohms. You can control how much air is coming out of the balloon in a certain time by increasing or decreasing the thickness of the opening of the straw.

The air moving through the straw is current or amperes (amps). It’s the flow of the air.

The amount of air it takes to turn the pinwheel is power or watts. The bigger the pinwheel, the more movement of air and the more pressure it takes to turn the pinwheel. A bigger pinwheel is more work. A 100 watt lightbulb is more work than a 40 watt lightbulb for a transformer to light.

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6. ### RodeoTexPoster Extraordinaire

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^^^ thanks, but I don't need to use my imagination. I use my test equipment every day.
You can use a straw and think about things in reverse but that doesn't do much in the real world, right here, right now when there's a problem.
Sorry, not being ugly.

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7. ### Torren61Tele-Afflicted

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I’m breaking it down in a simple thought experiment. That’s not really meant for you. I reread what you posted. Yeah, it is a measure of how much work the circuit is doing, as you already know. But the work itself is wattage. No offense taken.

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8. ### RodeoTexPoster Extraordinaire

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9. ### Digital LarryTele-Afflicted

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I use garden hoses and water for my electrical analogies that nobody likes to listen to (it's my kids mostly). And I go back to physics class definitions for everything whether it seems intuitive or not.

Work is something like carrying a box upstairs. You increased its potential energy, because now it can fall downstairs. Unit of work is (pardon my English) - "foot-pounds". Power is a measure of how quickly you carried it upstairs - "foot pounds per second".

Current by itself is simply a measure of how many electrons went past a given point in a second - "coulombs per second". We can't calculate power or work in that scenario because the load was not defined. 1 amp into a 1 ohm load is a different amount of power than 1 amp into a 10 ohm load, even though the current is the same.

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10. ### rigateleTele-Afflicted

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The amp is defined as the thing you plug into.

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So is that 1.602×10^-19 is the smallest possible volt charge?
I am still struggling to understand these basics.

12. ### David BarnettDoctor of Teleocity

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I guess they couldn't find two conductors of infinite length and negligible circular cross-section, much less put them in a vacuum.

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This made me curious about Lord Kelvin. Was he a lord to begin with or was he knighted for his work? Wiki knows all:

William Thomson, 1st Baron Kelvin, OM, GCVO, PC, FRS, FRSE (26 June 1824 – 17 December 1907) was an Ulster Scots Irish [5][2] mathematical physicist and engineer who was born in Belfast in 1824. At the University of Glasgow he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging discipline of physics in its modern form. He worked closely with mathematics professor Hugh Blackburn in his work. He also had a career as an electric telegraph engineer and inventor, which propelled him into the public eye and ensured his wealth, fame and honour. For his work on the transatlantic telegraph project he was knighted in 1866 by Queen Victoria, becoming Sir William Thomson. He had extensive maritime interests and was most noted for his work on the mariner's compass, which previously had limited reliability.

Absolute temperatures are stated in units of kelvin in his honour. While the existence of a lower limit to temperature (absolute zero) was known prior to his work, Lord Kelvin is known for determining its correct value as approximately −273.15 degree Celsius or −459.67 degree Fahrenheit.

He was ennobled in 1892 in recognition of his achievements in thermodynamics, and of his opposition to Irish Home Rule,[6][7][8] becoming Baron Kelvin, of Largs in the County of Ayr. He was the first British scientist to be elevated to the House of Lords. The title refers to the River Kelvin, which flows near his laboratory at the University of Glasgow. His home was the red sandstone mansion Netherhall, in Largs. Despite offers of elevated posts from several world-renowned universities, Kelvin refused to leave Glasgow, remaining professor of Natural Philosophy for over 50 years, until his eventual retirement from that post. The Hunterian Museum at the University of Glasgow has a permanent exhibition on the work of Lord Kelvin including many of his original papers, instruments, and other artifacts, such as his smoking pipe.​

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14. ### Junior LittleTele-Meister

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Getting to work at the National Institute of Standards and Technology does make for some interesting photo opportunities.
I might not understand everything I see, but I sure do get to meet and chat with some interesting people.

15. ### Junior LittleTele-Meister

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16. ### ClashCityTeleTele-Meister

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Yeah, but a 100 watt lightbulb looks much better on stage...and it's louder, eh brighter. Eh...?

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17. ### ClashCityTeleTele-Meister

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So...Lord Kelvin invented Amps.
GOD BLESS HIM.
You can't beat a bit of physics.

18. ### sudogeekTDPRI Member

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1.602x10^-19 coulombs is the charge of the electron (coulombs not volts). It’s not the lowest possible charge, it’s just the charge of the electron, but it’s considered a fundamental constant. [The quarks that are thought to compose baryons have charges of -1/3 and +2/3 (relative to the charge of the electron defined as -1). Perhaps the quark will be subdivided in the future.]

If you want to think of current as flow of electrons past a point, then an ampere is the flow of 6.25x10^18 electrons per second.

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19. ### SilverfacePoster ExtraordinaireAd Free Member

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But what if you made a pinwheel the same size - but lighter? Or shaped to use the air differently (more or less efficiently)? What about the friction at the pin?

But mainly, what'a the practical application of this stuff when it comes to amps in general? "Amp Central Station" isn't "Ampere Central Station" - my guess is over 90% of the readers don't have a clue what this means in terms of their playing.

I LIKE the historical stuff posted by the OP - but when others hijacked it into math-based My brain left the building.

My thinking about these kinds of threads (and no offense meant) - the OP was providing some kinda interesting historical info from his workplace, which is cool.

But before taking something "fun" and turning it into a deep study of math and physics, please "consider the audience (or "readers")" and how many care about what you're posting.

20. ### Torren61Tele-Afflicted

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My post was meant to explain BASIC electricity and the terms used in a way most people can understand. It wasn't meant to be a college course on electrical theory.

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