Sound Waves
4 marks · NormalTwo musical instruments, a violin and a cello, each produce a note and their sounds are shown as oscilloscope traces.
Describe how you can tell from the trace which instrument produces the higher-pitched note.
Explain what happens to the loudness of the sound if the amplitude of the wave on the oscilloscope is increased.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) The instrument with more complete waves per second (higher frequency) on the oscilloscope produces the higher-pitched note.
(b) Increasing the amplitude increases the loudness of the sound heard.
Common mistakes: Confusing amplitude (loudness) and frequency (pitch)
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Mentions higher frequency or more waves per time for higher pitch.
B1 (a) · 1 mark · Correctly relates this to pitch (not amplitude).
B1 (b) · 1 mark · Recognises that amplitude is related to loudness.
B1 (b) · 1 mark · States that greater amplitude means greater loudness or volume.
Worked solution
a) The instrument with more waves per second (higher frequency) on the oscilloscope produces the higher pitch/note. Pitch depends on frequency, which is shown by the number of waves in a fixed time.
b) Increasing the amplitude of the wave increases the loudness of the sound. Amplitude shows energy/loudness, not pitch.