# email transfer

Discussion in 'Physics' started by leedictu, Aug 8, 2005.

1. ### leedictu Thread Starter New Member

Aug 8, 2005
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A question of interest. If I drop a pebble in a pond, movement is initiated and transferred in waves. If I initiate an electrical switch, impulse moves to the desired article. Circuitry flows through conductors; air is not a conductor. My question is-
what physical flow of wave/impulse/ electrons/whatever occurs when I strike a key on my computer keyboard and the image appears instantly on a computer screen in, say, New Zealand or Alaska.
This is purely an exercise in curiosity; nevertheless, I would be grateful for a reply. My knowledge of physics is at high-school level, plus a lively interest in reading articles on physics (not quantum) over the past sixty years.
Thank you for any response.

Lee Dickman.

2. ### Dave Retired Moderator

Nov 17, 2003
6,960
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Hi Lee,

Circuitry flows through conductors; air is not a conductor. My question is-
what physical flow of wave/impulse/ electrons/whatever occurs when I strike a key on my computer keyboard and the image appears instantly on a computer screen in, say, New Zealand or Alaska.

Current flows through conductors, which is merely the flow of electrons. If you are looking at what happens when you sent something over the internet, when we look at physical wired connections it really is as simple as that. Wireless distribution, of information refers to the propagation a signal which flows through the air, there is no current flow in the same sense as a wired conductor, however power (energy) is still present - this is the key factor. It is the same with phone communictations where the information is embedded with a signal of a particular power density (energy).

I'd be interested if anyone could elaborate on the above.

Aug 8, 2005
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4. ### kanan New Member

May 4, 2007
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Air is a conductor having impedance. Electric current (electrons) are transformed to electromagnetic wave energy and electric wave enegry (similar to sunlight enegy traveling thru air). These waves have capacity to carry information without use of copper conductors. A radar or satellite can receive these information and convert back to electric current, which leads to communication of information.

5. ### Papabravo Expert

Feb 24, 2006
10,340
1,850
Air is a pretty good insulator at DC. EM energy is radiated from conductors with AC currents in them. I don't think electrons get transfomed into anything but electrons, (The Identity Transform), at least at energies below those found in a cyclotron.

6. ### recca02 Senior Member

Apr 2, 2007
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according to my understanding,
a keystroke will be like a digital signal (similar to electric current say pulsating dc)
by modem this signal encoded into a analogue signal .
then this signal goes over the telephone line after which or in some case directly
it is modulated, i believe like other signals and possibly by the use of transponders it is sent to different places over the world after which the reverse process of bringing signal into its original digital form is carried out and
decoded by pc to show you the same information typed before.
this i believe is the basic idea for transmission of any signal through air.
i:e to modulate a carrier frequency which is in the em range to carry a signal.

so like mr dave had said its more like a flow of energy like light carrying information.

light also carries information. you might be able to see dinosaurs if you can
catch the light that is abt that many lightyears far from now.(good news
for elvis fans)

if u want to get a feel of these things like encoding a data on a em wave, consider this hypothetically funny case:
a laser can easily travel to moon, now suppose you are sending a morse code using pulses of laser ,u'll be encoding
a signal in form of pulses which will be decoded by a person there to get your message, he may also transmit this data to some other planet perhaps with a different type of code (remorse code ) in this case he plays the role of trans reciever.
i dont think i can make it more simpler and absurd but its good for understanding the concept of data transmission in a nutshell.

7. ### leberk New Member

May 5, 2007
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Wow so many subjects so little time.
Light waves are electromagnetic in nature just a much higher frequency than is used for Radio and TV.
Once a wave, of any frequency is initiated it travels in all direction forever.
Modem is an acronym for Modulation-Demodulation.
The digital signals generated by computers go through the Modem conversion process many times on their journey. By the way it isnt instantaneous. Light and Radio waves travel at the same speed, 186 thousand miles per second.
By the way what was the question?

8. ### leberk New Member

May 5, 2007
7
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Lee,
Yr statement "Circuitry flows through conductors; air is not a conductor."
Needs a little clarification. Air can be both conductor and insulator depending on the situation. In the case of a Capacitor the space between the Pos and Neg plates requires a dielectric with high insulating properties. If only Air separates the two terminals, depending on the spacing, it will break down and conduct when enough voltage is applied. Even with a good dielectric the charge will eventually dissipate when the voltage is removed.

9. ### Dave Retired Moderator

Nov 17, 2003
6,960
145
Unless the energy in the wave is transfered into another form (i.e. heat) upon incidence with an object. This is like saying the wave is not reflected.

Dave