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Ohms law


Guest Farnsbarns

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Guest Farnsbarns

[laugh] Because of Ohms, Amperes are restricted to about two third the speed of light. Yet it makes the depicted context too hard to see for the naked eye! [biggrin]

 

Doesn't really make sense. Amperes are an abstract concept, not a thing. Electrons, however, have been perceived as travelling as slow as 1.3mph through sodium at close to 0k. [thumbup]

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Doesn't really make sense. Amperes are an abstract concept, not a thing. Electrons, however, have been perceived as travelling as slow as 1.3mph through sodium at close to 0k. [thumbup]

[thumbup] You're definitely right, electrons move quite slowly within metals. The two third of the speed of light I mentioned is the speed of the propagating electric field within metal conductors with typical wave resistances. That's what makes me use video cables for the BNC word clock connections of my digital recording gear and terminate them appropriately.

 

The speed of light is achieved by the electric field within superconductors only, meaning that time stands still as for all photons free of friction. As nothing of this field appears outside the conductor, losses are virtually zero.

 

OK, I shut up now. [rolleyes]

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Ever been shocked? I am an electrician and I have. If you have ever been shocked you wont say amperes are an abstract concept.

In fact, ampere is the least abstract thing in electrics. Taking a look at physical units, it is the only base or fundamental unit like metre, kilogram, second, kelvin, mole and candela. All other units applying to electromagnetics, like volt, ohm, watt, coulomb, henry, farad, and about 40 more, are compound units as the few previously mentioned following here may show, and thus looking way more abstract to me:

 

V = kg * m2 *s-3 *A-1

Ω = kg * m2 *s-3 *A-2

W = kg * m2 *s-3

C = A * s

H = kg * m2 *s-2 *A-2

F = A2 * s4 * kg-1 * m-2

 

I hope I got them right - please check before use ;)

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Never took physics but I learned about a lot those electrical terms and what they are during my electrical training and schooling. I even when the extra mile and leaned who they were named after. Going off memory and not using google here goes. James Watt, George Simon Ohm, Andre Marie Ampere, Alessandro Volta, Michael Faraday, Carl Gauss, Joseph Henry, Nikola Tesla and James Maxwell. I know there is ton more I forgot.

 

Now name 10 thing you do thought the day that don't use electricity?

Impossible. Even scratching your @ss requires the firing of electrical impulses in the brain.

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1490400765[/url]' post='1844304']

Ever been shocked? I am an electrician and I have. If you have ever been shocked you wont say amperes are an abstract concept.

 

I have many times, hurts like H€}}. Split my thumb open once from a welder 440 hit in water. That was way back when we were told we had to weld underground pressure tanks in water standing on a thick board.

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I've been hit by 440VAC and it hurts. 110VAC in the USA is the deadliest cause its everywhere. All it takes is 1/10th on one Amp across your heart and you can die. Half an amp flows though a 60 watt light bulb. That is 5 times more amperage needed to make your heart stop.

 

440 and 220 have enough voltage to kick you away. 110 has just enough voltage to keep you hanging on. Even normalized to deaths/ 1000 incidents 110 is deadlier.

 

From Wikipedia: "A sustained electric shock from AC at 120 V, 60 Hz is an especially dangerous source of ventricular fibrillation because it usually exceeds the let-go threshold, while not delivering enough initial energy to propel the person away from the source."

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Guest Farnsbarns

22,000v is the highest voltage shock I've taken. Thankfully it was DC but there was no current limiting at all except my own resistance to ground. Always short the output from an LOPT in a cathode ray tube arrangement before starting work!

 

I've had 24OVAC at up to 35amps available but fused at 13amps about 5 times. Not nice.

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1490494028[/url]' post='1844551']

I have many times, hurts like H€}}. Split my thumb open once from a welder 440 hit in water. That was way back when we were told we had to weld underground pressure tanks in water standing on a thick board.

 

At a place where I worked they had an old welder that was Knockout brand, if you accidentally touched yourself with the welding rod you just about got knocked out. A cousin of mine was welding in the inside of a combine with one like it, must of layed the stinger on his chest and stopped his heart. That's the way they found him dead.

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Coulomb was a cool guy. He figured out that things that carry a charge attract or repel each other in proportion to the charges on them and the square of the distance between them. And some other electrical stuff too. In the 1700's.

 

Then on the weekend he figured out how retaining walls and unstable slopes fail and developed the engineering models for what's called active and passive soil pressure theory. The exact same methods used today to design retaining walls, slopes and dams.

 

He wore nice outfits too.

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