Medical imaging (pre-natal scans):
- Ultrasound pulses sent into body
- Reflects off tissue boundaries (where density changes)
- Time and intensity of echoes used to build up an image
- Non-ionising — safer than X-rays for developing babies
Industrial testing (SONAR):
- Finding cracks/flaws in metal structures
- Measuring thickness of materials
- Submarines/ships use SONAR to detect objects under water
Echo calculations:
distance = speed × time ÷ 2 (divide by 2 because sound travels THERE and BACK)
Quick Check: An ultrasound pulse takes 0.0001 s to return after being reflected from a foetus. The speed of sound in tissue is 1500 m/s. How far away is the foetus?
The pulse travels to the foetus and back, so the total path is speed × time = 1500 × 0.0001 = 0.15 m. The foetus is half that distance away: 0.15 ÷ 2 = 0.075 m (7.5 cm). Always halve the total path — the echo covers the distance twice.
This key facts covers Ultrasound Applications within Sound Waves for GCSE Physics. Revise Sound Waves in Waves for GCSE Physics with 16 exam-style questions and 15 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 5 of 13 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
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.