Explain why radio waves are used for broadcasting television and radio signals on Earth, whilst microwaves are used for satellite communications. Your answer should refer to the properties of both types of electromagnetic radiation.

Pearson Edexcel International GCSE Physics (4PH1) — 3.2 The electromagnetic spectrum · Explain · 4 marks · View as Markdown

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

Radio waves and microwaves are both types of electromagnetic radiation used in communications. Radio waves have wavelengths ranging from about 1 mm to 100 km, whilst microwaves have wavelengths of roughly 1 mm to 30 cm.

Model answer (4 marks)

Radio waves are reflected by the ionosphere, allowing them to be bounced around the curved Earth and reach receivers over very long distances, which is ideal for terrestrial broadcasting of radio and TV signals.
Microwaves, having shorter wavelengths and higher frequencies, are not reflected by the ionosphere but can pass straight through it. This makes them suitable for line‑of‑sight transmission to and from satellites orbiting above the ionosphere, enabling satellite communications.

Examiner tips

  • Use the word ‘reflected’ for radio waves and ‘pass through’ for microwaves; link each property to the application (broadcasting vs satellite).
  • Show the causal chain: ionosphere reflection → long‑range terrestrial use; ionosphere penetration → satellite use.
  • Keep the answer concise – 4 marks, so one sentence per point.
  • Use UK spelling (e.g., ‘television’).

Common mistakes

  • Confusing the direction of ionosphere interaction (e.g., saying microwaves are reflected).
  • Mixing up which radiation is used for which application.

Mark scheme (4 marks)

  1. Radio waves are reflected by the ionosphere (a layer of the atmosphere)
  2. This reflection allows radio waves to be sent/received over long distances around the curved Earth's surface
  3. Microwaves can pass through / penetrate the ionosphere (because they have a shorter wavelength / higher frequency than radio waves)
  4. This allows microwaves to be transmitted to and from satellites in orbit above the ionosphere, enabling satellite communications

Key terms in this question

radio waves · microwaves · electromagnetic radiation · satellite communications

Related

More The electromagnetic spectrum questions

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