# Signals

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

1. ### Jacky LukGuest

Hi,
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...
Thanks
J

2. ### Jacky LukGuest

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
1...
Thanks
J

3. ### Jacky LukGuest

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

4. ### jgreimerGuest

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 MastaGuest

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
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

6. ### Jacky LukGuest

Thanks everyone, understood the concept now
Jack