Physics (AS & A Level) · Feb / March 2018 · Paper 12 · Question 5

A person calculates the potential difference across a wire by using the measurements shown. Which measured quantity has the greatest contribution to the percentage uncertainty in the calculated potential difference? | | quantity | value | uncertainty | |---|---|---|---| | A | current / A | 5.0 | ± 0.5 | | B | diameter of wire / mm | 0.8 | ± 0.1 | | C | length of wire / m | 150 | ± 5 | | D | resistivity of metal in wire / Ω m | 1.6 × 10⁻⁸ | ± 0.2 × 10⁻⁸ |

1. Acurrent / A
2. Bdiameter of wire / mm
3. Clength of wire / m
4. Dresistivity of metal in wire / Ω m

As printed in the paper