Conductance is quite opposite to resistance, which is defined as the ease of the material to let the electric current pass through it. The higher the conductance the resistance decreases and vice versa, the higher the resistance, the less conductance, so that both are inversely proportional. If a material has a lot of conductance it will be a very good conductor.
The conductance of a material is inversely proportional to the resistance:
G = 1 / R
The conductance value “G” of a material is indicated in “siemens” and identified with the letter “S” .
There are some materials that conduct current better than others. The best conductors are, without a doubt, metals, mainly gold (Au) and silver (Ag), but due to their high cost in the market, it is preferred to use copper (Cu) first, and second second, aluminum (Al), as both metals are good conductors of electricity and have a much lower cost than gold and silver.
Other types of materials, such as nichrome wire (Ni-Cr, nickel-chrome alloy), constantan, manganin, carbon, etc. They are not good conductors and offer greater resistance to the passage of electric current, which is why they are used as such, that is, as “electrical resistances” to produce heat primarily, or to control the passage of current in electronic circuits.
Example : Room heaters uses nichrome wire resistance as the heating element.
WHAT IS CONDUCTIVITY
Conductivity, meanwhile, is the opposite of resistivity. The resistivity or specific resistance of a material is represented by the Greek letter “ ρ” (rho) *. Therefore, its inverse can be represented mathematically by means of the following formula, in which the Greek letter “ σ” (sigma) represents conductivity:
Similar to resistivity is for resistance, it is conductivity for conductance. The conductivity will be inversely proportional to resistivity:
σ = 1 / ρ
The higher the conductivity of any material or element, the more easily electric current will flow through the circuit. The conductivity unit of measure is the Siemens / m (S / m) .
In most formulas it is better to use the conductivity because they are usually integers. For example, copper at 20ºC has a resistivity of 0.017, but a conductivity of 56 Siemens / meter.