Describe the properties that all electromagnetic waves share, and explain why radio waves are considered less hazardous to human health than X-rays.

Edexcel GCSE Physics (1PH0) — 5.1 Light and the electromagnetic spectrum · Describe and Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

All electromagnetic waves are transverse waves.
All electromagnetic waves travel at the same speed in a vacuum (3 × 10⁸ m/s).
X‑rays have a higher frequency than radio waves.
Higher frequency waves carry more energy, so X‑rays can cause cell damage or mutations whereas radio waves do not carry enough energy to do this.

Examiner tips

Use the exact terms ‘transverse waves’ and ‘3 × 10⁸ m/s’. Show the frequency–energy link: higher frequency → higher energy → more damage. Keep the answer concise – one sentence for each point.
Avoid mixing up frequency and wavelength; remember energy ∝ frequency.

Common mistakes

Saying all EM waves are longitudinal. Using ‘speed of light’ instead of the exact value. Claiming radio waves have higher energy than X‑rays.

Mark scheme (4 marks)

All electromagnetic waves are transverse waves
All electromagnetic waves travel at the same speed in a vacuum (3 × 10⁸ m/s)
X-rays have a higher frequency than radio waves
Higher frequency waves carry more energy, so X-rays can cause cell damage or mutations whereas radio waves do not carry enough energy to do this

Key terms in this question

electromagnetic waves · X-rays · radio waves