ABSTRACT
From time to time some of the dimmer audio commentators speculate that metallic conductors are actually a kind of ‘sea of micro-diodes,’ and that non-linearity can be found if the test signal levels are made small enough. Copper is the preferred metal for conducting electricity in almost all circumstances. In contrast copper oxidises, and silver acquires a non-conductive coat of black silver sulphide. Tin-doped indium oxide has the extremely useful property of being both electrically conductive and transparent and is used on touch screens. Electrical cable is very often specified by its cross-sectional area and current-carrying capacity, and the resistance per meter is seldom quoted. Printed circuit boards (PCBs) are the standard way of doing electronics, apart from a few valve amplifiers that still use tag-boards and point-to-point wiring. Resistors for general PCB use come in both through-hole and surface-mount types. It is well-known that resistors have inductance and capacitance and vary somewhat in resistance with temperature.
