Interesting stuff on electric resistance I found in my physics book...

[TheMarchingMule]

Hey guys, I know this whole "does the material of a cable make a noticeable difference or not?" thing easily gets out of hand, but for awhile I wanted to quote these two paragraphs from my physics book "Conceptual Physics" by Paul G. Hewitt, published in 2002, on page 534.
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34.4 Electric Resistance

The amount of charge that flows in a circuit depends on the voltage provided by the voltage source. The current also depends on the resistance that the conductor offers to the flow of charge - the electric resistance. This is similar to the rate of water flow in a pipe, which depends not only on the pressure difference between the ends of the pipe but on the resistance offered by the pipe itself. The resistance of a wire depends on the conductivity of the material used in the wire (that is, how well it conducts) and also on the thickness and length of the wire.

Thick wires have less resistance than thin wires. Longer wires have more resistance than short wires. In addition, electric resistance depends on temperature. The greater the jostling about of atoms within the conductor, the greater resistance the conductor offers to the flow of charge. For most conductors, increased temperature means increased resistance.* The resistance of some materials becomes zero at very low temperatures.

* Carbon is an interesting exception. At high temperatures, electrons are shaken from the carbon atom, which increases electric current. Carbon's resistance decreases with increasing temperature. This behavior, along with its high melting temperature, accounts for the use of carbons in arc lamps.
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What do you civilized Head-Fi members think about this?

 

[colonelkernel8]

So maybe if we keep our cables in liquid helium at all times, they will sound better.

 

[shomie911]

Quote:

Originally Posted by colonelkernel8 /img/forum/go_quote.gif So maybe if we keep our cables in liquid helium at all times, they will sound better.

Don't let Patrick hear that

 

[Chu]

No offense, but there really isn't anything in there that most people who argue about cables around here do not know.

 

[Tachikoma]

Quote:

So maybe if we keep our cables in liquid helium at all times, they will sound better.

Considering the prices some high end cables have been marketed for I'm surprised that no-one has come up with something like this yet =P

 

[HumanMedia]

Quote:

Originally Posted by colonelkernel8 /img/forum/go_quote.gif So maybe if we keep our cables in liquid helium at all times, they will sound better.

I think you mean this as a joke, but its most likely true, as many materials superconduct at extremely low temperatures.

And if you are actually interested, have a look at the 5th state of matter - the Bose Einstein Condensate, and find out why materials superconduct at low temperatures.

 

[Chu]

It's been a while since I've taken any advance chemistry, but I thought the link between lamda-point transitions in superfluids and superconductivity were essentially disproven?

 

[LawnGnome]

I don't get it.

This is pretty much common knowledge is it not?

 

[jinp6301]

hopefully everyone knew this already

 

[Dept_of_Alchemy]

Quote:

Originally Posted by colonelkernel8 /img/forum/go_quote.gif So maybe if we keep our cables in liquid helium at all times, they will sound better.

I'm just surprised that no one has come out with superconducting ICs yet.

 

[MD1032]

Oh my gosh, I used that textbook in high school, and seriously, screw it. We barely covered anything, and what we did cover was so poorly explained, it was terrible.

What they're trying to say is:

V = IR

Voltage (in volts) = Current (in amperes) times Impedance (in ohms)

End story.

 

[rb67]

Yeah, pretty common knowledge I thought.....

For an interesting exercise, calculate the resistance of silver vs copper cables and you will see that it has practically no impact at all. Also, think about the traces on your circuit boards, how thin they are, and how much resistance those would have compared to the cable. You'll realize that with this information, resistance based on geometry has no impact at all.