http://www.smeter.net/ Fact of the Day

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"Feed-Line Impedance
Conditions for maximum power transfer through a transmission line require source and load impedances to be conjugates, respectively, of the line input impedances seen from each end with opposite-end terminations connected. However, conditions for no-reflections at the ends of a line require that source and load impedances equal line impedance. Those two requirements are mutually incompatible unless a line's impedance is pure resistance (i.e., unless a line's impedance has no inductive or capacitive reactance component). ©2004 Tigertek, Inc. All rights reserved."

 

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http://www.smeter.net/daily-facts/1/fact18.php

"Why Copper Ground Rods?
January 18th Fact-of-the-Day
Copper ground rods actually are copper clad steel, because copper rods would be too soft to drive in the ground and unnecessarily expensive. Most people probably assume that copper is used because of its high conductivity. That is a slight added advantage, but not the real reason. The resistance of the soil surrounding a ground rod is so high compared to the resistance of any metal that the series resistance of a rod and the soil surrounding it would be almost the same regardless of the metal used. The real reason copper is used is copper a noble metal that has high corrosion resistance. It becomes a cathode when joined together with a less noble metal such as steel in the presence of an electrolyte such as moist soil. The less-noble steel becomes a sacrificial anode that corrodes away first, leaving a relatively corrosion-free copper shell in contact with the soil. ©2005 Tigertek, Inc. All rights reserved."