MadSci Network: Physics
Query:

Re: Which is faster.

Area: Physics
Posted By: Bill Reisdorf, Post-doctorate Fellow, Biochemistry and Molecular Biophysics
Date: Thu Aug 28 10:24:49 1997
Area of science: Physics
ID: 872533621.Ph
Message:
Which is faster -- electricity or light?

Light wins! (sort of...)

This is because the speed of light is the ultimate limit.
According to Einstein's special theory of relativity nothing can go
faster than light. And nothing that has mass (weight) can ever quite
get to the speed of light, because it simply takes too much energy to
accelerate it that far. The electrical current carried by a typical
copper wire is actually carried by many millions of electrons which
are constantly bumping into one another and into other atoms in the
wire. This tends to slow them down so that they never get anywhere
near the speed of light. 

However, when you start studying physics in school -- one of my
favorite subjects -- you'll discover something neat. It turns out that
changing electric fields generate magnetic fields, and changing 
magnetic fields will generate an electric field. And light itself is
just an electro-magnetic field that oscillates at a frequency that our 
eyes are sensitive to, so we can see it. It was quite a surprise to
most physicists in the last century when it was demonstrated that
the speed of light was exactly the same as the speed of the electric
or magnetic field. They were all really the same thing!
So as it turns out, the electrical SIGNAL that is being transmitted
through a wire is actually moving at the speed of light, even though the
individual electrons which carry the current aren't traveling anywhere
nearly that fast. Cool, huh? Well, I suppose that's 
probably more than you wanted to know. I hope it didn't confuse you.
Thanks for asking!

--Bill Reisdorf--

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