A-level practical assessment - 5
Determination of resistivity of a wire using a micrometer, ammeter and voltmeter.
This CAP involves measuring the diameter of a wire in order to find its area before using it in a circuit to find how its resistance varies with length.
You will then be expected to use a graph to find its resistivity and cooment on the uncertainty in your results.
| Wire Diameter d/$\units{m}$ | Cross sectional area A/$\units{m^{2}}$ | |||
|---|---|---|---|---|
| 1 | 2 | 3 | Mean | |
| 4.6×10-4 | 4.2×10-4 | 4.3×10-4 | 4.4×10-4 | 1.5×10-7 |
- Range = $\quantity{4.0×10^{-5}}{m}$
- Absolute uncertainty = $±\quantity{2.0×10^{-5}}{m}$
- Percentage uncertaint in area = $±9.1\%$
| Length l/$\units{m}$ | Potential Difference V/$\units{V}$ | Current I/$\units{A}$ | Resistance R/$\units{Ω}$ | |||
|---|---|---|---|---|---|---|
| 1 | 2 | 3 | Mean | |||
| 0.100 | 0.50 | 1.27 | 1.25 | 1.24 | 1.25 | 0.40 |
| 0.200 | 0.50 | 0.68 | 0.68 | 0.70 | 0.67 | 0.73 |
| 0.300 | 0.50 | 0.51 | 0.51 | 0.50 | 0.51 | 0.99 |
| 0.400 | 0.50 | 0.38 | 0.38 | 0.38 | 0.38 | 1.32 |
| 0.500 | 0.50 | 0.29 | 0.29 | 0.29 | 0.29 | 1.72 |
| 0.600 | 0.50 | 0.25 | 0.25 | 0.25 | 0.25 | 2.00 |
| 0.700 | 0.50 | 0.21 | 0.21 | 0.21 | 0.21 | 2.38 |
| 0.800 | 0.50 | 0.19 | 0.19 | 0.19 | 0.19 | 2.36 |