ELECTRONS

[ggunn]

And I made up the whole thing.

Ah, well, what I posted is a real scene from the original Star Trek.

 

[ggunn]

No they don't. The actual crazy now is the miles of coiled fiber to simulate distance so your trade gets to Chicago, NY and Philly at exactly the same time even though you are in say Boston.

Sent from my LT26i using Tapatalk

Well, the story I heard (also on NPR, and if I understood it correctly) was that trading companies kept moving their computers closer and closer to the Exchange in New York to minimize the ping time to the Exchange's servers until they got to within a block or less of it. Now they are all in the same building in the same room, but things move so fast that the varying length of their connection cables afforded the ones on one side of the room with an advantage over the others, so they agreed (or were compelled by the SEC or whoever) to have the same length cables to stop the arms race for connection speed.

Whether that is exactly the case or not, they do enjoy a tremendous advantage over the rest of us and are suspected by some to use sophisticated algorithms and huge lightning fast buys and sells to rig the market for their own benefit.

 

[Smart $]

Kirk: What do you think our chances are of getting out of this alive?
Spock: Approximately 1 in 898.9853.
Kirk: Approximately.
Spock: (Lifting one eyebrow) Yes, captain.

Ah, well, what I posted is a real scene from the original Star Trek.

I can't say for certain that is not actual dialog, but an internet search turn up the following dialog:

Kirk: What would you say the odds are on our getting out of here?
Spock: Difficult to be precise, Captain. I should say approximately seven thousand eight hundred twenty four point seven to one.
Kirk: Difficult to be precise? Seven thousand eight hundred and twenty four to one?
Spock: Seven thousand eight hundred twenty four point seven to one.
Kirk: That's a pretty close approximation.
Spock: I endeavour to be accurate.
Kirk: You do quite well.

Source: http://en.wikiquote.org/wiki/Star_Trek:_The_Original_Series
Series references:
http://www.startrek.com/database_article/errand-of-mercy
http://en.wikipedia.org/wiki/Errand_of_Mercy

 

[__dan]

http://mobile.nytimes.com/2014/04/06/magazine/flash-boys-michael-lewis.html?referrer=&_r=0

Sent from my LT26i using Tapatalk

Great story. Had read it earlier but could not find the link to post it myself.

There's another great story out there where trading companies were building their own microwave links between Chicago and NYC because the speed of light is faster through the air than through optical fiber. Another story detected high volume spike trading milliseconds *before* the Fed interest rate news releases. Supposedly, reporters get the news 20 minutes before the release time, giving them time to wrote their stories, but are locked in a room for 20 minutes. Having that news one minute early can make you enough money to buy your own large country.

http://www.bloomberg.com/news/2013-11-26/speed-traders-meet-nightmare-on-elm-street-with-nanex.html

http://www.nanex.net/aqck2/4436.html

http://www.nanex.net/FlashCrash/OngoingResearch.html

 

[SMHarman]

Well, the story I heard (also on NPR, and if I understood it correctly) was that trading companies kept moving their computers closer and closer to the Exchange in New York to minimize the ping time to the Exchange's servers until they got to within a block or less of it. Now they are all in the same building in the same room, but things move so fast that the varying length of their connection cables afforded the ones on one side of the room with an advantage over the others, so they agreed (or were compelled by the SEC or whoever) to have the same length cables to stop the arms race for connection speed.

Whether that is exactly the case or not, they do enjoy a tremendous advantage over the rest of us and are suspected by some to use sophisticated algorithms and huge lightning fast buys and sells to rig the market for their own benefit.

Two different sets of traders
Market makers are more decentralised. The ones in the NYT article.
Prop traders put their machines by the exchange. They the write autonomous algorithms to react to the trade stream.

Sent from my LT26i using Tapatalk

 

[domnic]

electrons

electrons

From my calcs about:
0.006645669 in/sec
and
0.002658268 in/sec
respectively.

In the 10 amp wire are the electrons moving faster or more of them flowing the wire?

 

[ggunn]

I can't say for certain that is not actual dialog, but an internet search turn up the following dialog:

Kirk: What would you say the odds are on our getting out of here?
Spock: Difficult to be precise, Captain. I should say approximately seven thousand eight hundred twenty four point seven to one.
Kirk: Difficult to be precise? Seven thousand eight hundred and twenty four to one?
Spock: Seven thousand eight hundred twenty four point seven to one.
Kirk: That's a pretty close approximation.
Spock: I endeavour to be accurate.
Kirk: You do quite well.

Source: http://en.wikiquote.org/wiki/Star_Trek:_The_Original_Series
Series references:
http://www.startrek.com/database_article/errand-of-mercy
http://en.wikipedia.org/wiki/Errand_of_Mercy

That's probably correct. I haven't seen the episode in 40 years or so.

 

[Smart $]

In the 10 amp wire are the electrons moving faster or more of them flowing the wire?

From a basic theory perspective, it's not one or the other. Ignoring a wire's reactive characteristic where AC is involved, it is the same number of electrons flowing faster. There would be more electrons passing a cross sectional plane at any one instance, but the number that enter one end of the wire is the same as the number that leave the other end at [almost] the same instance. The number of electrons in the wire remain [relatively] constant.

 

[Besoeker]

In the 10 amp wire are the electrons moving faster or more of them flowing the wire?

0.006645669 in/sec is faster than 0.002658268 in/sec

 

[mbrooke]

The number of free (able to move to conduct current) electrons in the wire is proportional to the mass of the wire. The number of electrons passing through a given cross section per unit time will be proportional to the current.
So the product of the number and the speed will increase with the current.
I have not seen an authoritative source, but my gut feeling is that it is the speed which increases as you increase the current in a given conductor.
The moving electrons then "run into" the stationary electrons (not free to move) causing both the IR voltage drop and the heating.

Tapatalk!

So given resistance actually slows electrons down?

 

[Smart $]

So given resistance actually slows electrons down?

That's the only thing which slows them down.

If the resistance is below a certain threshold point upon energizing, there will be no doubt as to what is traveling at the speed of light... :blink:

 

[mbrooke]

That's the only thing which slows them down.

If the resistance is below a certain threshold point upon energizing, there will be no doubt as to what is traveling at the speed of light... :blink:

but after words we are talking about 0.024 centimeters a second? You could watch them flow at that speed?

 

[rlundsrud]

electron drift calculation

electron drift calculation

What you are actually talking about is the drift velocity of an electron (Vd). The variables at play for this calculation are:

1. Free charge density of the conductor. . For copper it is 8.46x10^28 e/m^3
2. The current that is being carried. (I)
3. The cross sectional area of the conductor. (A)
4. We also need the charge of the electron. (q) 1.6x10^-19 c

The formula for calculating electron drift is:

Vd=I/nqA

So if we had 10 amps of current and a cross sectional area of 3.15x10^-4 m^2, we would have:

10/(8.46x10^28 e/m^3)(1.6x10^-19 c)(3.14x10^-4 m^2)= 2x10^-6 m/s


If the length of the conductor was 1 meter long it would take 118.064 hours to travel this distance. While seems iimpossible, it is very true but the analogy of a hose with water in it applies. If it is full of water when the hose is turned on water will immediately flow from the end, but a single molecule of water will take much longer to travel the distance from the faucet to the end of the hose.

Bob

 

[mbrooke]

What you are actually talking about is the drift velocity of an electron (Vd). The variables at play for this calculation are:

1. Free charge density of the conductor. . For copper it is 8.46x10^28 e/m^3
2. The current that is being carried. (I)
3. The cross sectional area of the conductor. (A)
4. We also need the charge of the electron. (q) 1.6x10^-19 c

The formula for calculating electron drift is:

Vd=I/nqA

So if we had 10 amps of current and a cross sectional area of 3.15x10^-4 m^2, we would have:

10/(8.46x10^28 e/m^3)(1.6x10^-19 c)(3.14x10^-4 m^2)= 2x10^-6 m/s


If the length of the conductor was 1 meter long it would take 118.064 hours to travel this distance. While seems iimpossible, it is very true but the analogy of a hose with water in it applies. If it is full of water when the hose is turned on water will immediately flow from the end, but a single molecule of water will take much longer to travel the distance from the faucet to the end of the hose.

Bob

So with a piece of 12 guage copper and a 60hz current electrons only move about a millimeter back and forth each cycle? So those electrons just sway back and fourth so to speak?


I know, hard to grasp. I was taught that electrons moved close to the speed of lightBut that's why I'm here, Im learning!:thumbsup:

 

[fmtjfw]

So with a piece of 12 guage copper and a 60hz current electrons only move about a millimeter back and forth each cycle? So those electrons just sway back and fourth so to speak?


I know, hard to grasp. I was taught that electrons moved close to the speed of lightBut that's why I'm here, Im learning!:thumbsup:

According to Einstein's theory of special relativity, as an electron's speed approaches the speed of light, from an observer's point of view its relativistic mass increases, thereby making it more and more difficult to accelerate it from within the observer's frame of reference. The speed of an electron can approach, but never reach, the speed of light in a vacuum, c. However, when relativistic electrons?that is, electrons moving at a speed close to c?are injected into a dielectric medium such as water, where the local speed of light is significantly less than c, the electrons temporarily travel faster than light in the medium. As they interact with the medium, they generate a faint light called Cherenkov radiation

http://en.wikipedia.org/wiki/Electron

 

[mbrooke]

According to Einstein's theory of special relativity, as an electron's speed approaches the speed of light, from an observer's point of view its relativistic mass increases, thereby making it more and more difficult to accelerate it from within the observer's frame of reference. The speed of an electron can approach, but never reach, the speed of light in a vacuum, c. However, when relativistic electrons?that is, electrons moving at a speed close to c?are injected into a dielectric medium such as water, where the local speed of light is significantly less than c, the electrons temporarily travel faster than light in the medium. As they interact with the medium, they generate a faint light called Cherenkov radiation

http://en.wikipedia.org/wiki/Electron

That means they would be traveling backward in time

 

[GoldDigger]

That means they would be traveling backward in time

No. That would only correspond to exceeding the speed of light in a vacuum.
Cherenkov radiation is quite analogous to the sonic boom that a plane or bullet sheds when moving faster than the speed of sound in air. Also without moving backward in time.

Tapatalk!

 

[mbrooke]

No. That would only correspond to exceeding the speed of light in a vacuum.
Cherenkov radiation is quite analogous to the sonic boom that a plane or bullet sheds when moving faster than the speed of sound in air. Also without moving backward in time.

Tapatalk!

Thanks! Im getting finally:thumbsup:

 

[rlundsrud]

So with a piece of 12 guage copper and a 60hz current electrons only move about a millimeter back and forth each cycle? So those electrons just sway back and fourth so to speak?


I know, hard to grasp. I was taught that electrons moved close to the speed of lightBut that's why I'm here, Im learning!:thumbsup:

The function of the electron drift is affected by amperage and cross sectional area, all the other values are constants if using copper wire. For what its worth this is really a useless calculation unless your an engineering student and you want to pass the electricity and magnetism final in your engineering physics class. I can't think of any time I actually needed to use it.

Bob

 

[Besoeker]

The function of the electron drift is affected by amperage and cross sectional area, all the other values are constants if using copper wire. For what its worth this is really a useless calculation unless your an engineering student and you want to pass the electricity and magnetism final in your engineering physics class. I can't think of any time I actually needed to use it.

Bob

I guess you learn lot of stuff like that.
I'm blessed/cursed with a fairly good memory and remember things that I'll never use in real life. Like the permittivity of free space.
But maybe if I'd been designing capacitors rather than power electronics......