why isnt electricity instantaneous?

[cracked]

ive always heard electricity travels approximatly at light speed, but why isnt it instantaneous? my understanding is that electricity is not like an empty pipe with an electron starting at one end and going to the other, but rather it is a pipe full of electrons already and when one is added to one end another pops out on the other end. if this is so it seems to me that the time it would take between adding an electron and having one on the other end "pop out" would be zero. can anyone offer a simple explanation to this?

thanks!

drew

[ben-the-slacker]

I think electricity is slightly slower than lightspeed. As for the electron thing, I think the electrons bumps along. When electricity comes into contact with an electron, that electron bumps the electron next to it, and that one bumps the next one, and so on. That's why it's not instant, because it travels through that bumping process.

[Bill in SD, CA]

Good explanation Ben!

How fast would lightning be if it didn't zig-zag?

Bill

[Theophylact]

Even if electrons were like ball-bearings filling a pipe completely from end to end, if you pushed one additional ball-bearing in at one end it would take some time for another to pop out at the far end. The motion is transmitted by a compression wave, the speed of which is the speed of sound in the medium (steel, for ball-bearings).

[cracked]

ok. i get it now, bc there is an amount of space between the electrons and it takes time to"get to one another" as they bump along.

new idea: consider this. you have a pipe. it is filled with some sort of balls, like pingpong balls or something. the balls are all touching one another and there is no compression factor on the balls, in other words they cannot be "squeezed" at all. if you push another ball into the pipe, it will force one out on the other end. if one were to devise some sort of code to comunicate with depending on how often the balls are pushed out or something like that, then would this not be instantaneous comunication? i know it would be impractical over long distances, but it makes sense to me anyway...

drew

[no1_vern]

The first thing that comes to mind is that Electricity is traveling through a METAL medium. Light also SLOWS down when it travels through a medium also. Link : http://micro.magnet.fsu.edu/primer/l...edoflight.html

Quote "When light traveling through the air enters a different medium, such as glass or water, the speed and wavelength of light are reduced (see Figure 2), although the frequency remains unaltered. Light travels at approximately 300,000 kilometers per second in a vacuum, which has a refractive index of 1.0, but it slows down to 225,000 kilometers per second in water (refractive index of 1.3; see Figure 2) and 200,000 kilometers per second in glass (refractive index of 1.5). In diamond, with a rather high refractive index of 2.4, the speed of light is reduced to a relative crawl (125,000 kilometers per second), being about 60 percent less than its maximum speed in a vacuum."

Interesting java applet on speed of light through various materials :
http://micro.magnet.fsu.edu/primer/j...ght/index.html

About electricity, its like ben said each electron bumps against its neighbor and eventually gets to the end of the cable-albeit slower that light speed.

[OuTpaTienT]

Originally posted by cracked
ok. i get it now, bc there is an amount of space between the electrons and it takes time to"get to one another" as they bump along.

new idea: consider this. you have a pipe. it is filled with some sort of balls, like pingpong balls or something. the balls are all touching one another and there is no compression factor on the balls, in other words they cannot be "squeezed" at all. if you push another ball into the pipe, it will force one out on the other end. if one were to devise some sort of code to comunicate with depending on how often the balls are pushed out or something like that, then would this not be instantaneous comunication? i know it would be impractical over long distances, but it makes sense to me anyway...

drew

No, it's not that simple.

Electricity flows by way of electrons transferring from one atom to the next, as people have already explained here.

Those electrons inhabit a space around the nucleus of each atom. They don't orbit around the nucleus as many people think. The space they inhabit are called Orbitals. The electrons can be found anywhere within their Orbital at any given time.

Maybe you're thinking that the particles that make up atoms (protons, neutrons, electrons) are all very close together in tidy little bundle…but they're not. For example, imagine a simple hydrogen atom; just one neutron and one electron. Now, imagine if we could enlarge that atom until the neutron is about the size of single green pea. Where do you think the electron would be? Or a better way to ask would be, how large is the electron's Orbital now that we enlarged the atom? Would it be right there around pea? Maybe a few inches outside of the pea? … No. The Orbital would extend up to a quarter-mile away from the pea!

And this HUGE amount of space that is occupied by the electron cannot be compressed or changed. At least not with our current science.

In a nutshell, all I'm saying is you cannot draw relationships between particles on the atomic or sub-atomic level with any "normal" sized object like ping pong balls or ball bearings or whatnot. The laws of physics are different at the atomic level.


Atomic Orbitals

Atomic Structure

[Target]

Since nobody has mentioned it yet, I believe the speed of electricity (at least over wire) is 3 nano-seconds per meter.

[osprey4]

David DiVincenzo at the IBM Thomas J. Watson Research Center offers this response:

All current computer device technologies are indeed limited by the speed of electron motion. This limitation is rather fundamental, because the fastest possible speed for information transmission is of course the speed of light, and the speed of an electron is already a substantial fraction of this.