How Do Fiber Optic and Copper Cables Differ in Physics?

[Grove1996]

Hey

I am about to start a research paper on the physics concepts involved in relation to fibre optic cabling and copper cabling. In my report I have to discuss how the physics in both relate and differ from one another. In terms of fibre optic cabling I have decided to talk about snell's law and the associated variables/concepts that go with it. However, I am unsure what to talk about in relation to copper cabling. This is my last major piece in my last year of high school and I really want to do well. I know the main differences between the two, but I'm unsure what to focus on in particular when it comes to copper cabling. If anyone has any suggestions or links to post that might be useful that would be great.

Regards,
Grove1996

 

[johnbbahm]

You can address the topic from ether a high level of the differences or a low level.
From a high level Fiber Optics tend to have a much better signal to noise ratio, and are immune to
electrical noise.
Copper on the other hand is easy to install, and passes data in the same physical format as most
electronic systems (electrical current).

At the low level, it might help to think about a square pulse of energy sent into both mediums.
In the fiber, the pulse is a concentration of photons moving along like a wave.
As the wave moves, some of the photons take shorter bounce paths, some longer.
Over distance this difference in speed, looks like dispersion, the crisp edges of the
pulse start spreading over a broader time window.
In the copper the pulse is a voltage difference, that interacts with the capacitance and
resistance of the cable. In copper cabling this effect can occur in very short cable runs.
On a scope both effect look alike, (the energy is spread over a broader time),
but are unrelated in cause.