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Discussion in 'Electronic Basics' started by Jacky Luk, Aug 19, 2005.

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  1. Jacky Luk

    Jacky Luk Guest

    I remembered I read from a book in which it roughly said
    "The drift rate of an electron is about 35cm/h (I can't confirm this figure
    now cos I did not know where the book I read was)"
    So if it is the case, how come the signal coming from the source instantly
    appeared on its output at a lightning speed... There was also a reference
    which said electric current is like a water pipeline, the electron just
    pushes the one on in front of it which creates an instantanous "Power
    transfer"? and I understand this. But what about signals? why the signal
    also has the same speed (due to electric field)? What is the significance
    of frequencies (Megahertz/Gigahertz, 3GHz CPU, 400MHz RAM etc) in such
    cases? There is more to ask for this question because I just made up my mind
    last night so I've forgotten...
  2. Jacky Luk

    Jacky Luk Guest

    Take the internet as an example,
    If I put an 1 onto the network, how come the other one
    in the other side of world (the remote computer) knows I am speaking of an
  3. Jacky Luk

    Jacky Luk Guest

    So My question why the signal is passed on so fast!!!!
    That's what I can remember from yesterday....
  4. jgreimer

    jgreimer Guest

    When you speak, do the molecules of air travel from your mouth all the way
    to the ears of the listener? No? How does the sound get there so fast?
  5. Bob Masta

    Bob Masta Guest

    The water-in-a-pipe analogy is OK, but I prefer to think
    of it as a pipe full of marbles or bearing balls. You can
    also build a nice little demonstrator to show this. You
    push a marble in one end, and another "instantly" pops
    out of the other. The marbles all push on each other
    and the force propagates at the speed of sound (in marbles).
    The analogy with electrons would be the speed of light.

    Now, about signal propagation: Just imagine you push a
    marble, wait a second, push another, wait 2 seconds or
    whatever... the marbles that came out the other end
    would be different marbles than the ones that went in,
    but they would move on the same schedule. And if all
    the marbles look identical, then you won't be able to
    tell that they weren't the same ones that went in...
    just like you can't tell with electrons.

    Hope this helps.

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    Home of DaqGen, the FREEWARE signal generator
  6. Jacky Luk

    Jacky Luk Guest

    Thanks everyone, understood the concept now
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