In my EM book, Wentorth, he used the example of a transmission line as an infinite line of charge. The book states "...a test charge placed a couple of centimeters from an elevated transmission line will see what appears to be an infinite length line (of charge)." I'm confused why this would appear to be a line of charge if there is an equal amount of positive and negative charges inside the transmission line or conductor. It would seem to me that a single conductor would appear as an infinite line of current. While a transmission line would seem like two opposite direction lines of current.