Why is it that some materials fight the flow of electricity while others embrace it?
Electrical conductivity is defined as a measure of how readily a material allows an electric current to pass through it. This is in contrast to electrical resistivity, which is a measure of how strongly a material opposes the flow of an electric current.
The precise conductivity level of a material is found by determining its magnitude of current density by the magnitude of its electric field. Simply put, this means that a material that can pull a large amount of current through it – even with an intrinsically small electric field – is a good conductor due to its low resistivity to electron flow.
Electron flow is characterised in a meta 1 by the dissociation of its atoms’ outer electrons from its structural lattice. These free electrons, when an electrical potential difference (ie voltage) is applied, proceed to travel from one end of a material to the other under the influence of its internal electric field.
The ability and quantity of these electrons to flow un-interrupted -something that can be hampered by irregular lattices and the thermal motion of ions – dictates how much current can be effectively carried through a material. If either of these factors is excessive, then the free electrons will scatter easily from their path through the material, reducing the amount of current that can pass through, which makes for a higher resistance.
Examples of good electrical conductors include copper, gold and silver – the latter being the most electrically conductive of all metals. However, don’t be fooled into thinking that non-metallic materials are not capable of conducting electricity, as plasma, salt solutions and even the carbon-based graphite all can boast high conductivity levels.