A student uses both an analogue stopwatch and a digital stopwatch to time the same event. Explain one advantage of using a digital device rather than an analogue device for measuring a time interval.

Cambridge International IGCSE Physics (0625) — 1.1 Physical quantities and measurement techniques · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

A digital stopwatch displays the time directly on a screen, so the user does not have to read a scale.
This eliminates parallax or human reading error.
Digital watches usually have finer divisions (e.g. 0.01 s) than analogue ones (≈0.1 s), giving greater precision.
Hence the time measured with a digital device has a smaller uncertainty and is more reliable.

Examiner tips

  • Use the phrase ‘direct display’ to show the advantage of no reading error.
  • Mention the finer scale division to justify greater precision.
  • Explain how this leads to a smaller uncertainty.
  • Keep the answer concise and use UK spelling.

Common mistakes

  • Failing to note that the display removes reading error.
  • Confusing analogue precision with digital precision.
  • Using vague terms like ‘more accurate’ without explaining the reason.

Mark scheme (4 marks)

  1. A digital device displays the measurement directly (on a display) / does not require the user to read from a scale
  2. This removes / reduces the possibility of (parallax / human) reading error when taking the measurement
  3. A digital device typically has a smaller scale division / greater precision than an analogue device (e.g. reads to 0.01 s compared to 0.1 s for analogue)
  4. Therefore the measurement obtained from the digital device has a smaller (percentage) uncertainty / is more reliable

Key terms in this question

analogue device · digital device

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