An ultrasound probe receives echoes from the front and back surfaces of an organ. The echoes arrive 30 μs30\ \mu\mathrm{s}30 μs apart. Ultrasound travels through the organ at 1600 m/s.
What is the thickness of the organ along the ultrasound path?
48 mm48\ \mathrm{mm}48 mm
12 mm12\ \mathrm{mm}12 mm
96 mm96\ \mathrm{mm}96 mm
24 mm24\ \mathrm{mm}24 mm
112 exam-style questions on Edexcel GCSE Physics 4.3 Sound, ultrasound and infrasound, covering 4.3.1 Sound waves, vibrations and the human ear, 4.3.2 Ultrasound and infrasound, 4.3.3 Uses of ultrasound and infrasound, and 4.3.4 Sound waves passing between media. Each one has a worked solution and a mark scheme showing where the marks go.