A student conducts an investigation into the electrical properties of a new conductive, highly-flexible gel-polymer filament used in soft robotics.
The student uses a physical vernier caliper to measure the diameter d d\,d of a uniform cylindrical specimen of the gel-polymer filament.
Suggest one problem with using a mechanical vernier caliper to make this measurement.
Table 1 shows the diameter measurements made by the student at five different points along the filament.
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 |
|---|---|---|---|---|
| 10.2 | 9.8 | 10.1 | 10.4 | 9.5 |
Calculate the percentage uncertainty in the diameter ddd. Assume all data are valid.
The length of this gel-polymer filament specimen is measured as 150±3 mm150 \pm 3\text{ mm}150±3 mm.
Determine the absolute uncertainty, in mm3\text{mm}^3mm3, in the volume of the filament.
The student molds the gel polymer into cylinders of various lengths, maintaining a constant volume of 4.50 × 10-5 m3.
The length L L\,L and resistance R R\,R of each molded specimen are measured. It can be shown that:
R=ρL24.50×10−5 R = \frac{\rho L^2}{4.50 \times 10^{-5}} R=4.50×10−5ρL2where ρ \rho\,ρ is the resistivity of the conductive gel polymer.
A graph of R R\,R against L2 L^2\,L2 is plotted, and the gradient of the line of best fit is determined to be 820 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.