The resistivity of a wire is determined from the relation
PHYSICS · Multi-part · A Level · Physics · Measurements and their errors · Measurements and their errors
Problem
The resistivity ρ of a wire is determined from the relation ρ=RA/ℓ, where R is the resistance, A the cross-sectional area, and ℓ the length of the wire.
(a) The following measurements are recorded:
• Resistance R=12.8Ω
• Length ℓ=1.235m
• Area A=0.00065m2
Rewrite each of these three quantities in scientific notation with the correct significant figures.
(b) Calculate the resistivity of the material in Ωm and express the answer in scientific notation, retaining the correct number of significant figures.
(c) Identify which one of the three measured quantities limits the number of significant figures in the final value of ρ and justify your answer with reference to the rules of significant figures in multiplication and division.