GCSE Physics resources

AQA GCSE Waves

Sound, Ultrasound and the Ear

Sound is longitudinal and needs particles to transfer vibrations. Ultrasound has a frequency above the human hearing range and can be used for imaging and cleaning because it reflects at boundaries or transfers energy.

AQA 8463 GCSE Physics Higher

Start here

The revision snapshot

Sound is longitudinal and needs particles to transfer vibrations. Ultrasound has a frequency above the human hearing range and can be used for imaging and cleaning because it reflects at boundaries or transfers energy.

By the end, you should be able to:

  • Use sound as a mechanical wave.
  • Apply the waves model, evidence or method to an unfamiliar exam context.
  • Recognise and correct this wrong turn: Calling sound an electromagnetic wave.

Before you revise

Diagnostic question

Choose an answer from memory. Your result tells you what to watch for in the guide.

Which statement correctly summarises sound, ultrasound and the ear?

Core revision guide

Learn the model, then use it

Sound, Ultrasound and the Ear questions become manageable when the central model, evidence and exam method are kept together. Read the explanation, test the misconception and then apply the idea without looking back.

Use sound as a mechanical wave

Sound is longitudinal and needs particles to transfer vibrations. Ultrasound has a frequency above the human hearing range and can be used for imaging and cleaning because it reflects at boundaries or transfers energy.

Build the physics picture

Sound is a longitudinal mechanical wave, so it needs particles and cannot travel through a vacuum. Ultrasound has a frequency above human hearing. Reflections from boundaries between materials can be timed to locate an object or build an image.

The relationship for this guide

Wave speed: v = fλ (m/s, Hz, m). Choose each relationship from the physical change described, convert quantities into compatible units and keep the unit beside the final answer.

A longitudinal sound wave has compressions and rarefactions and an ultrasound pulse reflects from a material boundary.
Sound needs particles; ultrasound is above 20 kilohertz and echo time can locate a boundary.Open the full-size exam diagram
Wave speedv = fλm/s, Hz, m

Misconception clinic

Replace the tempting answer

Read each belief, say what is wrong with it, then compare your correction.

Tempting idea: Calling sound an electromagnetic wave.

Use instead: Sound is longitudinal and needs particles to transfer vibrations. Ultrasound has a frequency above the human hearing range and can be used for imaging and cleaning because it reflects at boundaries or transfers energy.

Tempting idea: Using total echo distance as depth.

Use instead: Sound is a longitudinal mechanical wave, so it needs particles and cannot travel through a vacuum. Ultrasound has a frequency above human hearing. Reflections from boundaries between materials can be timed to locate an object or build an image.

Tempting idea: Mixing pitch (frequency) with loudness (amplitude).

Use instead: Use compression/rarefaction language, state the frequency condition and link the application to reflection or energy transfer.

Retrieval practice

Quick checks

1. Which exam method is most reliable for sound, ultrasound and the ear?

2. Which statement correctly applies sound, ultrasound and the ear to a question?

3. A pupil writes: “Calling sound an electromagnetic wave.” Which replacement is accurate?

Worked examples

See the method being built

These examples expose the difference between a secure use sound as a mechanical wave method and the common error “Calling sound an electromagnetic wave.”.

Example 1 · No sound in space

Explain why astronauts need radios in space.

  1. Sound needs particles.
  2. Space is near vacuum.
  3. Radio waves are electromagnetic.
Show the answer

Sound cannot travel through a vacuum because there are no particles to vibrate; radios use electromagnetic waves.

Example 2 · Ultrasound distance

An ultrasound pulse returns after 0.020 s; speed in tissue 1500 m/s. Find boundary distance.

  1. Total path = vt.
  2. 1500 × 0.020 = 30 m round trip.
  3. Divide by 2.
Show the answer

Distance = 15 m.

Example 3 · Ear response

Explain why very loud sound can damage hearing.

  1. Larger amplitude means stronger vibrations.
  2. Link to eardrum/hair cells.
  3. State potential damage.
Show the answer

Large-amplitude vibrations can damage sensitive structures in the ear.

Exam precision

Exam technique: Use sound as a mechanical wave

Do this: Use compression/rarefaction language, state the frequency condition and link the application to reflection or energy transfer.

Independent practice

Exam-style questions

Write an answer before opening the marking guidance. Then edit the exact phrase or step that would gain the next mark.

1. State whether sound is transverse or longitudinal.

[1 mark]
Show marking guidance and model answer

Marking guidance: Award one mark for the precise statement shown in the model answer.

Model answer: Longitudinal.

2. State why sound cannot travel in a vacuum.

[1 mark]
Show marking guidance and model answer

Marking guidance: Award one mark for the precise statement shown in the model answer.

Model answer: It needs particles to transfer vibrations.

3. Define ultrasound.

[2 marks]
Show marking guidance and model answer

Marking guidance: 2 marks are available for relevant, linked physics points that match the model answer.

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

4. State one use of ultrasound.

[1 mark]
Show marking guidance and model answer

Marking guidance: Award one mark for the precise statement shown in the model answer.

Model answer: Imaging, cleaning or detecting flaws.

5. Explain how ultrasound imaging works.

[3 marks]
Show marking guidance and model answer

Marking guidance: Award up to 3 marks for distinct physics points joined into a clear cause-and-effect chain.

Model answer: Pulses reflect at boundaries; echo times are used to locate structures.

6. State what amplitude of a sound wave relates to.

[1 mark]
Show marking guidance and model answer

Marking guidance: Award one mark for the precise statement shown in the model answer.

Model answer: Loudness/energy transfer, not pitch.

Questions pupils ask

Sound, Ultrasound and the Ear FAQs

What is the main idea in Sound, Ultrasound and the Ear?

Sound is longitudinal and needs particles to transfer vibrations. Ultrasound has a frequency above the human hearing range and can be used for imaging and cleaning because it reflects at boundaries or transfers energy.

What mistake should I avoid in Sound, Ultrasound and the Ear?

Calling sound an electromagnetic wave. Sound is a longitudinal mechanical wave, so it needs particles and cannot travel through a vacuum. Ultrasound has a frequency above human hearing. Reflections from boundaries between materials can be timed to locate an object or build an image.

Useful next steps

Connect this guide to your next task

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