I know that resistance is inversely proportional to the cross sectional area, but I need to explain why with the following data:
Wire │ Length (m) │ Diameter (mm) │ Cross Section (mm) | Resistance (Ω) ────────┼────────────┼───────────────┼────────────────────┼─────────────── Wire 1 │ 1m │ 0.19mm │ 0.02835 mm │ 0.59 Ω ────────┼────────────┼───────────────┼────────────────────┼─────────────── Wire 2 │ 1m │ 0.31mm │ 0.07548 mm │ 0.22 Ω
I made a graph showing the inverse of the diameter compared to the resistance:
And one for the inverse of the cross sectional area:
But I don't know what to do now. If diameter was inversely proportional, then a wire with the average of the two diameters (0.25 mm) would also have an average of the resistances (0.405) but I can't disprove this (even though I know it isn't) because they haven't given us a third data point.
How can I use the data above to show that resistance is inversely proportional to cross sectional area?
For reference, here is a photo of the question I'm working from.