This topic summary covers Knowledge Organiser: Sound Waves within Sound Waves for GCSE Physics. Revise Sound Waves in Waves for GCSE Physics with 13 exam-style questions and 15 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 13 of 13 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 13 of 13
Practice
13 questions
Recall
15 flashcards
Knowledge Organiser: Sound Waves
Key Terms
- Longitudinal: particles vibrate parallel to wave travel
- Compression: high-pressure region
- Rarefaction: low-pressure region
- Ultrasound: frequency > 20,000 Hz
- Infrasound: frequency < 20 Hz
Key Facts
- Sound speed: gas < liquid < solid
- Sound in air: ~330 m/s
- Cannot travel through vacuum
- Louder = bigger amplitude on oscilloscope
- Higher pitch = higher frequency on oscilloscope
Key Equations
- v = f × λ
- distance = (speed × time) ÷ 2 (echo)
- f = 1/T
Exam Tips
- Echo formula: always ÷2 for return journey
- Ultrasound = non-ionising = safe for foetuses
- Sound = longitudinal; EM waves = transverse
- Amplitude affects loudness; frequency affects pitch
Common Mistakes
- Forgetting to halve in echo calculations: The measured time is for the sound to travel to the object AND back — divide by 2 before multiplying by speed to get the one-way distance
- Saying sound travels faster in air than solids: Sound travels fastest in solids, then liquids, then slowest in gases — denser packing means vibrations transfer more efficiently
- Confusing amplitude and frequency effects: Amplitude determines loudness (volume); frequency determines pitch — a louder sound has larger amplitude, not higher frequency
- Saying sound is a transverse wave: Sound is a longitudinal wave — particles vibrate parallel to the direction of wave travel, creating compressions and rarefactions
- Saying ultrasound is ionising: Ultrasound is non-ionising — it is safe for medical imaging including foetal scans; X-rays are ionising and have associated risks
Revise this topic interactively on PrepWise — self-test mode, tap-to-reveal definitions, and Common Mistakes from examiners.
Try the interactive Knowledge Organiser — free →Keep building this topic
Read this section alongside the surrounding pages in Sound Waves. That gives you the full topic sequence instead of a single isolated revision point.
Practice Questions for Sound Waves
What type of wave is sound?
Describe how a sound wave is produced and how energy is transferred by a longitudinal wave.
Quick Recall Flashcards
13 questions on Sound Waves — practise free
Instant marking, adaptive difficulty, and 15 spaced repetition flashcards. Free until your GCSEs.
Try PrepWise Free