Conductive dough can easily be formed into different shapes to investigate the electrical properties of the material.
A student uses a digital micrometer screw gauge to measure the diameter d d\,d of a uniform cylinder made of the dough.
Suggest one problem with using a micrometer screw gauge to make this measurement.
Table 1 shows the diameter measurements made by the student.
Table 1
| d1 / mmd_1\text{ / mm}d1 / mm | d2 / mmd_2\text{ / mm}d2 / mm | d3 / mmd_3\text{ / mm}d3 / mm | d4 / mmd_4\text{ / mm}d4 / mm | d5 / mmd_5\text{ / mm}d5 / mm |
|---|---|---|---|---|
| 20.3 | 20.1 | 19.6 | 19.8 | 20.2 |
Calculate the percentage uncertainty in the diameter ddd. Assume all data are valid.
The length of this dough cylinder is measured as 80±2 mm80 \pm 2\text{ mm}80±2 mm.
Determine the absolute uncertainty, in mm3\text{mm}^3mm3, in the volume of the cylinder.
The student reforms the dough into cylinders of different lengths, each maintaining a constant volume of 3.14 × 10-5 m3.
The length L L\,L and resistance R R\,R of each cylinder are measured. It can be shown that:
R=ρL23.14×10−5 R = \frac{\rho L^2}{3.14 \times 10^{-5}} R=3.14×10−5ρL2where ρ \rho\,ρ is the resistivity of the conductive dough.
A graph of R R\,R against L2 L^2\,L2 is plotted, and the gradient of the line of best fit is found to be 1250 Ω m-2.
Determine ρ\rhoρ. State an appropriate SI unit for your answer.
37 exam-style questions on AQA A Level Physics Current electricity, covering Basics of electricity, Current-voltage characteristics, Resistivity, Circuits, Potential divider, and Electromotive force and internal resistance. Each one has a worked solution and a mark scheme showing where the marks go.