Use the data in Table to answer the following –
(a) Which among iron and mercury is a better conductor?
(b) Which material is the best conductor?
Table: Electrical resistivity of some substances at 20∘C
MaterialResistivity(Ωm)ConductorsSilver1.60×10−8Copper1.62×10−8Aluminium2.63×10−8Tungsten5.20×10−8Nickel6.84×10−8Iron10.0×10−8Chromium12.9×10−8Mercury94.0×10−8Manganese1.84×10−6AlloysConstantan(alloy of Cu Ni)49×10−6Manganin(alloy of Cu,Mn and Ni)44×10−6Nichrome(alloy of Ni,Cr,Mn and Fe)100×10−6InsulatorsGlass1010−1014Hard rubber1013−1016Ebonite1015−1017Diamond1012−1013Paper(dry)1012
(a) Resistivity of iron = 10.0×10−8Ω m
Resistivity of mercury = 94.0×10−8Ω m
The resistivity of mercury is more than that of iron. This implies that iron is a better conductor than mercury.
(b) It can be observed from the table that the resistivity of silver is the lowest among the listed materials. Hence, it is the best conductor.