directional cables?

Herman

Mr Simple, I decided the stuff in my last post about positive charges really didn't relate to your response so I deleted it.

Ah. I didn't know users could edit or delete their posts. Or are you a moderator?

I see what you mean but by defintion current is not the flow of electrons, it is the flow of charge. Since we're talking about cables then electrons are indeed moving about but you don't have to have moving electrons to have electric current since it is sometimes positive charges.

True enough. But since this thread is about cables and posted in the cable forum, I didn't think it terribly germane or productive to discuss electric current outside the context of cables.

Since the flow of charged electrons is relatively easy to envision it is used a lot, an analogy to water is often used even though it breaks down if you try to apply to all electrical phenomna.

Yes. But the issue under discussion is current flow. And the water analogy is perfectly adequate in this context.

However, I do know enough to understand that electron flow can't explain everything happening in electronics.

For example?

OK - water in garden hose it is.

Ah. I didn't know users could edit or delete their posts.
05-21-10: Simply_q

You sure can.... You only need to log in..... Then at the bottom of your post you are given the option to edit or delete the post.

Just click on (edit my post)

Now you can only edit your post until someone else posts a response....

Or after so many posts have been posted to the thread.... I believe 50, can't remember for sure.

Hi guys,

I think that in both this thread and the "speaker cable life span" thread a lot of the disagreement may be resulting from differing interpretations of the words "drift" and "flow."

If ac is applied to a cable, a given electron will "move" (aka "drift") an EXTREMELY small but non-zero distance during the first half-cycle of the waveform. During the second half-cycle of the waveform, it will move back to where it started. That movement will repeat for as long as the same signal is present.

On average, electrons at all points along a given conductor of the cable will do the same thing. The movement of electrons near the destination end of the cable will lag the movement of electrons near the driven end of the cable by a miniscule amount of time corresponding to the signal propagation velocity, which will be in the rough vicinity of 50 to 90% of the speed of light in a vacuum.

Although the individual electrons are moving back and forth across an infinitesimal distance, if we define a cross-section of the cable at any given point, and if ON AN RMS-AVERAGED BASIS, 6.241 x 10exp18 electrons move past that cross section in each second (in either direction), then 1 ampere of ac current is "flowing."

Meanwhile "charge" is conducted from one end of the cable to the other at near light speed, as I indicated. The charge is carried at the destination end of the cable by electrons that are not the same electrons as the ones near the source end of the cable, but which move similarly.

Agreed?

Best regards,
-- Al

Al - agreed. I objected only to term "Flow of electrons" since it has nothing to do with fast flow of charge. I stated also that with AC electrons are standing practically still - hardly a "flow of electrons". We can say that electricity (electrons) moves very slow but electric current (charge) moves very fast.