Silver metal. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm. At wavelengths shorter than 450 nm, silver's reflectivity is inferior to that of aluminium and drops to zero near 310 nm. Very high electrical and thermal conductivity is common to the elements in group 11, because their single s electron is free and does not interact with the filled d subshell, as such interactions (which occur in the preceding transition metals) lower electron mobility. The electrical conductivity of silver is the greatest of all metals, greater even than copper, but it is not widely
Electrical resistivity and conductivity equations can be worked out by hand, but for very accurate answers in complex cases, computer methods like finite element analysis may be required. In some applications where the weight of an item is very important, resistivity density products are more important than absolute low resistivity – it is often possible to make the conductor thicker to make up for a higher resistivity; and then a low resistivity density product material (or equivalently a high conductivity to density ratio) is desirable. For example, for long distance overhead power lines, aluminium is frequently used rather than copper (Cu) because it is