Editing Power transmission (section)

== Electrical power ==
{{Main|Electric power transmission}}
[[File:Electric transmission lines.jpg|thumb|Electric power transmission with overhead line.]]

With the widespread establishment of [[electrical grid]]s, power transmission is usually associated most with [[electric power transmission]].  [[Alternating current]] is normally preferred as its voltage may be easily stepped up by a [[transformer]] in order to minimize [[electrical resistance|resistive]] loss in the [[Conductor (material)|conductors]] used to transmit power over great distances; another set of transformers is required to step it back down to safer or more usable voltage levels at destination.

[[File:HV Cable.jpg|thumb|left|Electric power transmission with underground cable. Here (1) is the conductor for heavy currents and (3) the insulation for high voltages. {{Further|high-voltage cable}}]]

Power transmission is usually performed with [[Overhead power line|overhead line]]s as this is the most economical way to do so. Underground transmission by [[high-voltage cable]]s is chosen in crowded urban areas and in [[High-voltage direct current|high-voltage direct-current]] (HVDC) submarine connections.

Power might also be transmitted by changing [[electromagnetic field]]s or by [[radio waves]]; [[microwave]] energy may be carried efficiently over short distances by a [[waveguide]] or in free space via [[wireless power transfer]].