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back to article On the hunt for a new ampere

While there's been lots of attention paid to the search for a new kilogram, another of the SI system's fundamental units of measurement is under examination: the ampere. Along with the kilogram, metre, second, Kelvin, mole and candela, the ampere is one of the fundamental yardsticks used to measure the world around us. And, like …

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Boffin

SEP?

Sounds like Somebody Else's Problem*.

* Also thanks to Douglas Adams

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WTF?

Watt the ... ?

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Joke

Two cats on a bicycle.

When we've finally got the new kilogram and new ampere sorted out we can all be happy at last.

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Pint

Ugh...

We already have standard and metric tonnes, imperial, dry, and liquid pints and gallons, liters (or litres), miles and KPH to contend with. Will we have 20 metric-amp circuit breakers in our homes soon? I'm going to get a few pints of beer of some sort now... whichever measurement is more volume...

Can the reg come up with its own unit of measurement for electric current? Such as how many badgers you have to rub against a glass rod to produce enough current to light a 100W lamp?

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Coat

Re: Ugh...

African or European badger?

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Re: Ugh...

Martin, don't badger him.

ObQuote: "Badgers? We don't need no steekin' badgers!"

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Re: Ugh...

Mushroom

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Re: Ugh...

Spherical badgers, obviously.

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Re: African or European badger?

Either way, its a shitload of badgers

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Try to remember, kiddies ...

I could see the individual transistors, with my naked eye, on the first IC that I owned.

And that's just hardware.

Think about it.

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Coat

Re: Try to remember, kiddies ...

So what you're saying is that now they are I(don't)C transistors?

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Re: Try to remember, kiddies ...

No, Eddy, what I am saying is that we continue to learn about how the universe works, at a higher & higher resolution.

This is a good thing.

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Anonymous Coward

Re: Try to remember, kiddies ...

Well, we all know what makes you go blind!

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Pint

Re: Try to remember, kiddies ...

"Well, we all know what makes you go blind!"

Only if you get it in your eye

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Anonymous Coward

Re: Try to remember, kiddies ...

"No, Eddy, what I am saying is that we continue to learn about how the universe works, at a higher & higher resolution."

Really? Looked more like "I'll be a supercilious twat because I was getting into electronics/IT years before all of you (honest.)"

"This is a good thing."

No, it isn't.

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Mushroom

Re: All units are connected

.....the kilo ideally needs to be defined in terms fundamental constants such as the observed speed of light.

While in theory it would be possible to define the kilo as the amount of mass required to produce n [1] joules of energy when converted to same, thus basing it on the speed of light, measuring that accurately to derive a physical kilo for use in subsequent calibration of scales is probably impractical.

Icon to illustrate the slight snag in your idea.

[1] Where n is one fuck of a large number.

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Anonymous Coward

Just define the number of electrons in a coulomb, stupids!

Couldn't they could just define an exact number of electrons in a coulomb? And keep the ampere as a coulomb of charge per second? Seems pretty simples to me.

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Re: Just define the number of electrons in a coulomb, stupids!

Presumably you missed the bit where the value differs depending on how you measure it? Since that is a problem there therefore must be no good or valid way to determine which value to choose. Not to mention if it is wrong then other calculations using much more tightly defined units will have the accuracy of the result degraded by the Coulomb.

Which is why they are trying to do it properly instead.

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Happy

Re: Just define the number of electrons in a coulomb, stupids!

1 Ampere = 1 Hogshead of electrons.

Job done!

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C 7

What's all this rubbish?

What is it with trying to re-define the kilogram? Every sane person knows it's 2.2 pounds, so what's all the fuss about? If the damned frogs would just get with the program already and quit fussing around, we could get some serious work done, but no, it's all "kilo this" and "meter that." I mean, who the hell decided we needed a smaller unit of measure, which would be approximately 0.3937 inches? How the hell are reasonable people supposed to remember this drivel? Now we have wings that don't fit the airplanes they were built for, and spacecraft that miss their targets, all because some frogs can't figure out how to convert their dark-ages base-10 system into Real Units. Give me an inch and I'll take a mile, but leave the damn meters out of it unless we're talking cab fare.

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Anonymous Coward

Re: What's all this rubbish?

The French invented the kilometre to make French cars sound faster. The rest is all an attempt to make it look legitimate.

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Re: What's all this rubbish?

" I mean, who the hell decided we needed a smaller unit of measure, which would be approximately 0.3937 inches? "

Yep. Why would anyone want to measure anything to an accuracy greater then a furlong, perch , rod, bushel, chain, acre ? I mean come on now, why would you ? What good would it be ? What could you use it for ?

It was good enough for Grandad. Irony, isn't that a measure of how much iron is in a comment ?

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Re: What's all this rubbish?

Heaven forbid we try to make logical set of units that can be easily calculated in the head, and at the same time try to (other than the kilogram) define them exactly using universal constants.

That sounds terrible! Why don't we stick with a useless old mess?

That said, you can still use old units in informal settings, it's not like (as the Daily Mail would have you believe) someone from Brussels breaks down your door and takes you away for describing your DIY handwork in inches.

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Re: What's all this rubbish?

'The French invented the kilometre to make French cars sound faster'

True,

but that was the second attempt... the first involved a playing card and a clothes peg

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Joke

Re: What's all this rubbish?

The measure of irony in a comment is of course measured in Morisettes.

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Trollface

Re: What's all this rubbish?

... but that failed as it required the cars to move in the first place.

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Anonymous Coward

They need to create a framework

I suggest 20mtrs of 3"x2" fixed with 1kg of 6" nails

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Anonymous Coward

Re: They need to create a framework

Petrol sold in litres, road signs in miles. The uk never really 'got' the metric system. (These days I wonder what they're talking about when top gear insists on using horsepower, gallons, yards etc. The imperial system is so much an exercise in memory that few people bother memorizing any of it. How many yards in a mile? oh and Irish miles are different than english ones aren't they? Who knows how powerful a horse is anyway? Equestrians? What sort of horse? etc. but top gear and their fans love to hate anything French almost as much as I love to hate Clarkson)

P.s I am British and was taught metric from the beginning. actually school kids have been taught metric for 40 years, so there is understandable dissonance when the so called 'grown ups' continue to use the jumble of anti-mnemonic base 16 base 12 base whatever except 10 system.

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Re: They need to create a framework

ho ho ho

I know you jest, have you tried to buy a new tyre for your car lately?

eg

205/55/R16 91V

205mm _and_ 16 inches in the same fucking measurement. what genius came up with that?

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Re: They need to create a framework

Cloth is traditionally measured in yards in one direction and metres in the other --- because the looms that actually make the stuff were built premetricisation and are a yard across.

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Re: They need to create a framework

Or the N-gauge model railway scale

Two and one sixteenth millimetres to the foot.

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Headmaster

Re: They need to create a framework

"Mile" is (arguably) a decimal based unit; it's 1,000 Legionary (Roman) paces, thus the Latin "miles".

Errant pedantry, up with which we need not foot.

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Facepalm

Re: They need to create a framework

....Who knows how powerful a horse is anyway? Equestrians? What sort of horse? etc. but top gear and their fans love to hate anything French.....

Yes of course. Top Gear should use the continental system, in which a car's output is measured in "PS". This stands for "pferdestärke", which is german for, er, "horsepower".....

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The problem is how many electrons in an Ampere.

It's a lot.

The current devices (no pun intended) would take 1 x 10^13 secs to count that many electrons, the new hotness could knock that down by a factor of 10 000, which would still mean it takes about a year to run (roughly pi giga seconds in a year).

Thumbs up for upping the frequency of these little critters by a factor of 10 000.

Which in most other industries would be considered quite impressive.

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Boffin

Re: The problem is how many electrons in an Ampere.

"roughly pi giga seconds in a year"

Tsk. No. About 10 x pi megaseconds, unless your definition of roughly is very different to mine. Back to school, young man.

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Re: The problem is how many electrons in an Ampere.

Well it's electrons per second. So the speed you can count at limits the highest current you can measure. Additionally it's a bit hard to "scale" currents so it's hard to divide a current by a well defined factor.

Of course all of that is just theologic by definition since Metrology is just about the belief of something called "Reality" which can be explored by "measurements".

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Re: The problem is how many electrons in an Ampere.

There goes the cheap multimeter.

And small; where's my crane?

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Paris Hilton

First define your pinhead

All you need to do is define your pinhead, then the number of angels that can dance on it can better be thought about.

Though in fairness this new method has done that, with their quantum dot. A unitary pinhead.

Paris because she is an angelic pinhead.

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Joke

I love the smell of good science on a Monday morning..

...it smells like..smells like ozone.

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So does this mean my two multimeters that can measure down to 0.00000001A are wrong?

The manufacturer better have a decent calibration service then...

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Re: So does this mean my two multimeters that can measure down to 0.00000001A are wrong?

Yes, in the same way that the distances on road signs are wrong.

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Re: So does this mean my two multimeters that can measure down to 0.00000001A are wrong?

The distance on a road sign is an exact measurement to somewhere, just that it might not be to where you thought it was.

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Facepalm

Nice concept...

but I can't wait to see the little surprises when they try to compare those amp-meters devices in different labs. It's some decades now that they try to redefine the kg based on a well-define number of atoms and what sounded like a simple concept some decade ago became horribly complex and still doesn't work. Let's hope this one is different.

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Yardstick?

Yards have been deprecated. Don't you mean metre stick?

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What happens to the old one ?

When we get the new 'Ampere' defined, what happens to the old one ?

Does it get a nice retrement home ?

Do we then refer to it as 'GrAmpere' ?

Mine's the one with a pocket full of dead and alive cats.....

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Re: What happens to the old one ?

new kbd pls

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All I can say is GTF! Clearly the way we do things now is so terrible that buildings fall down because the measurements they use to build them are not accurate enough, and millions of electronic devices are blowing up left right and centre because the components used to build them are not rated tightly enough.....

What a joke - how much exactly are these new new (since we already have new) units of measurement a) costing to standardise and b) costing to integrate?

The speed and distance signs in the UK are what they are because it would simply cost far too much to change them...

I shall assume this is EU sticking it's fat wrinkly nose in again to further make life difficult for this country - because they come up with such fantastic ideas that make no sense (like the Cookie Law) which no-one else in EU bothers to implement - just the UK - at great expense.... (like the battery hens law)

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Ru

I shall assume this is EU sticking it's fat wrinkly nose in again

The Daily Mail is thattaway...

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Meh

Footnote to the footnote

The footnote gives the modern definition of the ampere in terms of its magnetic effect. When I was a lad, the ampere was defined in terms of its electroplating effect; viz: That quantity of current which is capable of depositing 62.10 grains of silver per hour from a silver nitrate solution.

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