What are some unusual conductors of electricity?
How about graphite and cadmium sulfide? Graphite, such as that in the lead of a pencil, conducts electricity even though it’s not formally a metal. If you draw a dark line on a sheet of paper, that line can act as a wire for sensitive electric circuits. Cadmium sulfide is a photoconductor—a material that is electrically insulating in the dark but that conducts electricity when exposed to light. Photoconductors of this sort are used in some light sensors, as well as in xerographic copiers and laser printers.