Geophysicists use low-frequency acoustic transmitters to study tectonic activity beneath the ocean floor. In seawater, where the speed of sound is 1500 m s-1, one of these transmitters emits a continuous, sinusoidal acoustic wave.
Which of the following wavelengths of this wave in seawater would classify it as infrasound?
7.5 mm7.5\text{ mm}7.5 mm
75 cm75\text{ cm}75 cm
7.5 m7.5\text{ m}7.5 m
120 m120\text{ m}120 m
35 exam-style questions on Edexcel GCSE Physics 4.3 Sound, ultrasound and infrasound (physics only). Each one has a worked solution and a mark scheme showing where the marks go.