Physics 9702 · AS & A Level · Errors and uncertainties
Errors and uncertainties — practice question
The readings for a sample of metal wire are given in Fig. 1.1. They are: length $1750\,\text{mm}$ with uncertainty $\pm 3\,\text{mm}$, diameter $0.38\,\text{mm}$ with uncertainty $\pm 0.01\,\text{mm}$, and resistance $7.5\,\Omega$ with uncertainty $\pm 0.2\,\Omega$.
(a(i))[1]
State the suitable instrument used to take the length measurement.
(a(ii))[1]
State the suitable instrument used to take the diameter measurement.
(a(iii))[1]
State the suitable instrument used to take the resistance measurement.
(b(i))[2]
Show that the resistivity of the metal comes out as $4.86 \times 10^{-7}\,\Omega\,\text{m}$.
(b(ii))[4]
Calculate the uncertainty associated with the resistivity.
(c)[1]
Use the answers in (b) to write the resistivity together with its uncertainty to the correct number of significant figures.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “metre rule or measuring tape (not rule)” …