conductor

Any material that conducts heat or electricity (as opposed to an insulator, or nonconductor). A good conductor has a high electrical or heat conductivity, and is generally a substance rich in loosely-held free electrons, such as a metal. Copper and aluminium are good conductors. A poor conductor (such as the non-metals glass, porcelain, and rubber) has few free electrons and resists the flow of electricity or heat. Carbon is exceptional in being non-metallic and yet (in some of its forms) a relatively good conductor of heat and electricity. Substances such as silicon and germanium, with intermediate electrical conductivities that are improved by heat, light, or impurities, are known as semiconductors.

Liquids (including water) can also be electrical conductors. Electricity (current) can flow by the movement of charged ions through a solution or a molten salt (electrolyte). This process is called electrolysis.

conductor

In music, the director of an orchestra who beats time, cues entries, and controls the overall expression and balance of a performance.

Conductors of ballet and opera are normally resident, on a full-time contract, available for the ongoing preparation of new repertoire. Conductors for symphony orchestras are more often freelance, star performers in their own right, under temporary contract for concert or recording purposes and thus more reliant on the expertise of orchestras.