Final answer:
To find the resistivity from a resistance vs. length plot, determine the slope of the line on the graph, and then multiply the slope by the constant cross-sectional area of the conductor.
Step-by-step explanation:
To calculate resistivity from a resistance versus length plot, you need to understand that resistance (R) of a conductor is proportional to its length (L) and inversely proportional to its cross-sectional area (A), according to the formula R = ρL/A where ρ (rho) represents the resistivity of the material. If you have a graph where resistance is plotted against the length for a conductor with a constant cross-sectional area, the slope of this graph will give you the resistivity of the material because R/L = ρ/A, which simplifies to ρ = slope × A.
You'll typically see a straight line if the material is ohmic, as resistivity for such materials is constant, which means that as length increases, resistance increases linearly. From the plot, determine the slope, and multiply it by the cross-sectional area of the conductor to find its resistivity. It's essential that the cross-sectional area remains constant for the lengths measured.