# A student is investigating the properties of a superconducting material. The student records the following measurements: a critical temperature of 0.000093 K above absolute zero, an electrical resistance of 0.000000047 Ω at room temperature, and a magnetic field strength of 0.0000003 T. Express each measurement using an appropriate SI prefix and explain why using SI prefixes is more useful than writing values in standard form for communicating measurements to other scientists.

> AQA A-Level Physics (7408) — 3.1.1 Use of SI Units and Their Prefixes · Explain · 5 marks

## Mark scheme (5 marks)

1. Critical temperature correctly converted: 93 μK (micro-kelvin) or 93 × 10⁻⁶ K
2. Electrical resistance correctly converted: 47 nΩ (nano-ohm) or 47 × 10⁻⁹ Ω
3. Magnetic field strength correctly converted: 300 nT (nano-tesla) or 0.3 μT (micro-tesla)
4. SI prefixes are more compact / easier to read / avoid writing many zeros or long decimal numbers
5. SI prefixes are internationally recognised / standardised so scientists worldwide understand the same units without ambiguity

## Key terms

- [SI prefix](https://www.gradenine.co.uk/glossary/si-prefix)

## Related

- [Revision notes for AQA A-Level Physics (7408)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-is-investigating-the-properties-0e7af0d4) · Published by Druglandscape Ltd.