Free GCSE Physics lesson: Sound and Seismic Waves
Aplailasain by Static Carnival

Free Lessons -> GCSE / Key Stage 4 -> Physics -> Sound and Seismic Waves

Lesson 44 · GCSE / Key Stage 4 · Physics

Sound, ultrasound and seismic waves

Compare sound, ultrasound and seismic waves, including reflection, echoes, imaging and Earth structure.

Qualification: GCSE Subject: Physics Waves Separate Physics and Combined Science where these wave applications are taught

Waves

This lesson builds sound, ultrasound and seismic wave applications for GCSE Physics.

Use the core lesson first, then match the exam-board guidance to your school route. Many pupils meet this content through Combined Science as well as Separate Physics.

Good forSeparate Physics and Combined Science where these wave applications are taught
FocusSound, ultrasound and seismic wave applications
Time45-60 minutes
EquipmentCalculator and wave-speed equation practice.
Paper fitPaper 2 focus on most GCSE Physics routes
TierFoundation and Higher core
Practical linkNo required practical focus
Maths tagsM1 units and equation sense

What you will learn

  • Describe sound as a longitudinal wave.
  • Use echoes and time delay to calculate distance.
  • Explain ultrasound imaging and sonar in simple terms.
  • Compare P-waves and S-waves in seismic evidence.

Exam-board fit

RouteSeparate Physics and Combined Science where these wave applications are taught
PaperPaper 2 focus on most GCSE Physics routes
TierFoundation and Higher core
Specification fitWaves: Sound, ultrasound and seismic wave applications
Practical linkNo required practical focus
Maths ladderM1 units and equation sense

Exact paper labels and specification-point numbering vary by board and cohort, so match this lesson to your school route before using past-paper questions.

Wave application scenarios supplied on this page

Use echo, ultrasound scan, sonar and earthquake examples to practise wave application explanations.

Clear explanation

Sound is a longitudinal wave that needs a medium. It cannot travel through a vacuum because there are no particles to vibrate.

Ultrasound has a frequency above human hearing. Reflected ultrasound pulses can build images or measure distances using time delay.

Seismic P-waves and S-waves travel differently through Earth. S-waves do not travel through liquids, which provides evidence about Earth's outer core.

Worked examples

Echo distance

A sound pulse takes 0.40 s to travel to a wall and back.

The total journey is twice the distance to the wall.

If sound speed is 340 m/s, total distance = 340 x 0.40 = 136 m.

Answer: The wall is 68 m away because the sound travelled there and back.

Quick checks

Choose an answer, then check your thinking.

1. Why can sound not travel through a vacuum?

2. Which seismic wave cannot travel through liquids?

Practice questions

Question 1

A sonar pulse returns after 0.20 s. The sound speed in water is 1500 m/s. How far away is the object?

Reveal answer and marking guidance

Answer: 150 m.

Marking: Credit total distance 1500 x 0.20 = 300 m, then halve for there-and-back journey.

Question 2

What is ultrasound?

Reveal answer and marking guidance

Answer: Sound with frequency above the upper limit of human hearing.

Marking: Credit frequency above about 20 kHz.

Question 3

Why are echoes useful in imaging or distance measurement?

Reveal answer and marking guidance

Answer: The reflected wave and its time delay show where a boundary or object is.

Marking: Credit reflection and time delay.

Question 4

What does the behaviour of S-waves suggest about Earth's outer core?

Reveal answer and marking guidance

Answer: The outer core is liquid because S-waves do not pass through it.

Marking: Credit S-wave evidence and liquid outer core.

Exam practice ladder

AO1 fluencyRecall the key definition, unit, equation or model before using the lesson questions.
AO2 applicationApply sound, ultrasound and seismic wave applications to an unfamiliar device, practical setup or data description.
AO3 analysisUse evidence, graph features, uncertainty, method quality or conclusion wording where the question asks you to evaluate.
Maths skillM1 units and equation sense

Answers and marking guidance

The exact practice answers are hidden under each question so you can try first. For this lesson, marks come from using the correct physics model, choosing the right equation where needed, keeping units with values, and explaining changes with precise words such as transfer, resultant force, acceleration, evidence and uncertainty.

Common mistakes

  • Forgetting to halve echo distances.
  • Calling sound transverse in air.
  • Thinking ultrasound is electromagnetic radiation.
  • Saying S-waves pass through liquids.

Exam-board guidance

All supported routes assess the core physics idea, but they may group topics, practicals and paper wording differently.

AQA GCSE Physics

AQA GCSE Physics: use this lesson for sound, ultrasound and seismic wave applications, then check whether your class is taking Separate Physics or Combined Science.

OCR GCSE Physics

OCR GCSE Physics: the core physics idea is shared, but Gateway and Twenty First Century may organise questions differently.

Pearson Edexcel GCSE Physics

Pearson Edexcel GCSE Physics: practise the concept, the equation use and the practical language because questions often connect them.

Eduqas GCSE Physics

Eduqas GCSE Physics: learn the core explanation and practise applying it to unfamiliar contexts, data and practical questions.

WJEC Wales

WJEC Wales: check whether your class is using the current GCSE Physics route or a newer science route, then use this lesson for the shared physics idea.

CCEA GCSE Physics

CCEA GCSE Physics: connect the idea to your unit and remember that practical skills are assessed directly.

Extension challenge

Compare ultrasound scanning and X-ray imaging, including one advantage and one limitation of each.

Reveal answer

Example answer: A strong extension response names the physics model, uses accurate units and explains why the evidence supports the conclusion.

Next lesson

Next, continue with Required Practical: Reflection and Refraction.

Previous lesson: Infrared PracticalBack to GCSE Physics lessonsNext lesson: Required Practical: Reflection and Refraction