ReviseRush logoREVISERUSH

Edexcel GCSE Physics

Waves and the electromagnetic spectrum — Edexcel GCSE Physics revision

Free revision notes, key terms, common exam traps and 5 practice questions with answers. About 4 minutes to read.

Wave basics

  • Transverse waves vibrate at right angles to the direction of travel (light); longitudinal waves vibrate along it (sound).
  • Wave speed = frequency × wavelength.
  • Frequency is waves per second in hertz; period = 1 ÷ frequency.

Electromagnetic spectrum

  • Order from longest wavelength: radio, microwave, infrared, visible, ultraviolet, X-ray, gamma.
  • All travel at the same speed in a vacuum.
  • Higher frequency waves carry more energy and can be more dangerous — UV, X-rays and gamma are ionising.

Key terms

Wavelength
Distance between the same point on two adjacent waves.
Amplitude
Maximum displacement from the rest position.
Ionising radiation
Radiation with enough energy to remove electrons from atoms.
Period
The time taken for one complete wave oscillation.
Refraction
The change in speed and direction of a wave as it passes into a different medium.
Electromagnetic spectrum
The continuous range of EM waves ordered by frequency and wavelength, from radio to gamma.

Common exam traps

  • Saying sound is transverse — it is longitudinal.
  • Measuring amplitude from peak to trough instead of from the middle line.
  • Mixing up frequency and wavelength when the speed is constant (they are inversely related).

Practice questions with answers

  1. 1. A wave has frequency 50 Hz and wavelength 4 m. Calculate its speed.

    Answer: 200 m/s

    v = f × λ = 50 × 4.

  2. 2. Which has the highest frequency?

    • • Radio waves
    • • Infrared
    • • Ultraviolet
    • • Gamma rays

    Answer: Gamma rays

    Gamma sits at the high-frequency, high-energy end.

  3. 3. Sound waves are:

    • • Transverse
    • • Longitudinal
    • • Electromagnetic
    • • Ionising

    Answer: Longitudinal

    The particles vibrate parallel to the direction of travel.

  4. 4. Define amplitude.

    Answer: The maximum displacement of a point on the wave from its rest position.

    Not peak to trough — that is double the amplitude.

  5. 5. What type of wave is sound?

    • • Transverse
    • • Longitudinal
    • • Electromagnetic
    • • Standing only

    Answer: Longitudinal

    Sound waves have vibrations parallel to the direction of energy transfer.

Keep going in the app

This topic has 63 questions in total, plus flashcards, cram mode and Grade 9 Push challenges.

Open the full topic Quick-fire quiz

More free Physics revision

ReviseRush is an independent educational revision aid. It is not affiliated with, endorsed by or connected to AQA, Edexcel, OCR, WJEC, Pearson or any exam board. All notes and questions are original. Always check content against your official course and specification. No grade outcome is guaranteed.