A physics student is recording measurements taken during an experiment. The student records a current of 0.000 006 A and a power of 3 500 000 000 W. Explain how the student could rewrite each of these measurements using the most appropriate prefix, and state the name and symbol of the prefix used in each case.

Edexcel GCSE Physics (1PH0) — 1.1 Key concepts of physics · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

0.000 006 A = 6 µA (micro‑ampere) – micro (µ) = ×10⁻⁶ (one millionth).
3 500 000 000 W = 3.5 GW (giga‑watt) – giga (G) = ×10⁹ (one billion).

Examiner tips

  • Use the correct prefix name and symbol in the answer.
  • Show the conversion factor (×10⁻⁶ or ×10⁹) to justify the choice.
  • Write the rewritten value in standard form (e.g. 6 µA, 3.5 GW).

Common mistakes

  • Writing 0.000 006 A as 6 mA (milliamps) instead of µA.
  • Using the wrong multiplier (e.g. ×10⁻³ for micro).
  • Omitting the prefix symbol (µ or G) in the rewritten value.

Mark scheme (4 marks)

  1. States that 0.000 006 A should be rewritten using the prefix micro (µ), giving 6 µA
  2. Links micro to the correct multiplier of ×10⁻⁶ (or 'one millionth') to justify the choice for 0.000 006 A
  3. States that 3 500 000 000 W should be rewritten using the prefix giga (G), giving 3.5 GW
  4. Links giga to the correct multiplier of ×10⁹ (or 'one billion') to justify the choice for 3 500 000 000 W

Key terms in this question

prefix

Related

More Key concepts of physics questions

▶ Try answering this question with AI marking (free) →