A factory uses an ultrasound sensor to monitor a rubber conveyor belt. The sensor sends a pulse into the belt and detects echoes from its near and far surfaces. The belt is 12 mm thick, and ultrasound travels through it at 1500 m/s.
What is the time difference between the two echoes?
32 μs32\ \mu\mathrm{s}32 μs
1.6 μs1.6\ \mu\mathrm{s}1.6 μs
16 μs16\ \mu\mathrm{s}16 μs
8.0 μs8.0\ \mu\mathrm{s}8.0 μs
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.