Science Buddies: "Ask an Expert"

i have a college investigation which i need help on the questions i need answered is
1)compare ring and radial feeders and the advantages and disadvantage of the 2 systems.
2)With the aid of diagrams, compare the construction of overhead and underground cables used for the transmission and distribution of electrical energy. discribe the properties of each material used in the construction of the cables and justify their application.

i have looked very hard but haven't found the rite stuff would be very helpfull if someone can help
thanks

Regarding transmission lines, here's some useful information: http://www.osha.gov/SLTC/etools/electri ... lines.html

And here's some information about ring vs. radial feeders:
http://www.tpub.com/content/engineering ... 071_43.htm

To help with future searches, here are the keywords I used in Google to find these pages: "underground transmission line" and "radial feeder ring".