Signals

[Jacky Luk]

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

 

[Jacky Luk]

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

"Jacky Luk" <jl@knight.com> źśźgŠóślĽóˇsťD:4305a4a9$1@127.0.0.1...

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

 

[Jacky Luk]

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

"Jacky Luk" <jl@knight.com> źśźgŠóślĽóˇsťD:4305a9a6$1@127.0.0.1...

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

"Jacky Luk" <jl@knight.com> źśźgŠóślĽóˇsťD:4305a4a9$1@127.0.0.1...
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

 

[jgreimer]

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?

"Jacky Luk" <jl@knight.com> wrote in message news:4305aba0$1@127.0.0.1...

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

"Jacky Luk" <jl@knight.com> źśźgŠóślĽóˇsťD:4305a9a6$1@127.0.0.1...
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

"Jacky Luk" <jl@knight.com> źśźgŠóślĽóˇsťD:4305a4a9$1@127.0.0.1...
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

 

[Bob Masta]

On Fri, 19 Aug 2005 17:21:53 +0800, "Jacky Luk" <jl@knight.com> wrote:

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

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
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

[Jacky Luk]

Thanks everyone, understood the concept now
Jack
"Bob Masta" <NoSpam@daqarta.com> źśźgŠóślĽóˇsťD:4305cc23.1667789@news.itd.umich.edu...

On Fri, 19 Aug 2005 17:21:53 +0800, "Jacky Luk" <jl@knight.com> wrote:

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


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
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Home of DaqGen, the FREEWARE signal generator

 

[Kitchen Man]

On Fri, 19 Aug 2005 17:21:53 +0800, "Jacky Luk" <jl@knight.com> wrote:

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)

OK, I think you said that you understand that the energy of an
electric field moves a bit less than the speed of light, while the
actual electron drift is significantly slower.

The significance of signal frequency is bandwidth and processing
speed. You appear to be asking about the speed of CPU and memory in a
computer, so the answer is rather simple there. The 3GHz CPU you
speak of has a clock rate of 3GHz, meaning it can process one simple
instruction in 1/3,000,000,000 second, or one every 0.333 nanoseconds.
This in comparison to the ancient 100MHz Pentium I, which processed
one simple instruction every ten nanoseconds. Memory access speed is
a similar calculation, with some caveats depending on type of memory.

Bandwidth of transmitted information is another subject entirely.