Volts = "The volt is defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power".
http://en.wikipedia.org/wiki/VoltWatt = power per second
http://en.wikipedia.org/wiki/WattAmps = Electric Charge per second
http://en.wikipedia.org/wiki/AmpereVolts, Watts and Amps are related to each other is the following Formula:
Watts = Volts/Amps
Ohm = Resistance (Direct currents only, impedance in AC Currents)
http://en.wikipedia.org/wiki/OhmOhm are best seen in Ohm' law:
Amps = Volts/Ohms
http://en.wikipedia.org/wiki/Ohm%27s_lawBut also read :
http://hypertextbook.com/physics/electricity/resistance/Which points out Ohm's law is more a guideline then a true scientific law. It also points out the Resistance of various elements the three important ones are as follows:
Aluminum 26.5
Copper 17.1
Silver = 15.9
Thus Copper has about 1/3 less Resistance to Electrical charge then Aluminum, the big issue is then the price of each AND the weight needed to be kept up. Silver is even better then Copper, but the price difference between Copper and Silver rules out Silver as a electrical wiring except in certain special situations.
Once you looked at the Resistance (ohms) then you look at the Voltage, Amps and Wattage. Remember the Formula: Volts=Watts/Amps
A good place to calculate between materials (Through mostly for areas):
http://www.allmeasures.com/Formulae/static/formulae/electrical_resistivity/2.htmGiven the above what is the difference between a 115Kv line and an 500 Kv Line?
First lets look at the test for Electrical Conductivity for aluminum
Then for Copper for 1000 meter long cable 10x10Cm square (I know cables are round but 10/10 is easier to calculate then the area of a Circle so I am using a Square for the Cable width):
That comes to:
0.0016775708773695 ohms
http://www.allmeasures.com/Formulae/d1/d2/d3/Results2_2.asp?formula=3&material=Copper+
Now for Aluminum for the same length and width:
0.026518164942985943
http://www.allmeasures.com/Formulae/d1/d2/d3/Results2_2.asp?formula=3&material=Aluminum+
As you can see Copper is preferred unless we have a some other reason to pick aluminum (Generally price AND the cost of installing the Wiring, aluminum is a lot lighter).
The switch from a 115kv to a 500 kv means a need for a much thicker wire to handle the increase electrical charge going through the wire. Remember Weigh increase by roughly a factor OF three AS YOU DOUBLE THICKNESS. Thus you are increasing the thickness of the wire by a factor of Five (May be less) the weight will have to increase by a factor of 15. This means an increase in the strength of the towers to handle the increase weight.
The main reason to go to 500 kv, is to increase electrical power through the system. A 115kv system is limited by its Amperage and Voltage, if you increase both (and that is what they are during going to a 500 kv Line) you can increase Wattage per hour, which is the real goal, for people use WATTS.
Just same observation if no one else answers your question.