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Practice questions · Loudness and pitch

Taller, or more waves?

Six original Cambridge-style questions. They test the two pairings, how to read and compare oscilloscope traces, and the classic mistake of swapping amplitude and frequency.

Original questions All questions on this page are original work, written in the Cambridge IGCSE style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Two pairings, never crossed

Amplitude with loudness. Frequency with pitch.

01
[2 marks]

State which property of a sound wave determines:

(a) the loudness of the sound, [1] (b) the pitch of the sound. [1]

(a) The amplitude. ✓

(b) The frequency. ✓

02
[2 marks]

Define the amplitude and the frequency of a wave.

  • Amplitude is the maximum displacement of a point from its rest (undisturbed) position. ✓
  • Frequency is the number of complete vibrations (or waves) per second, measured in hertz. ✓
03
Analysis
[2 marks]

A sound is displayed on an oscilloscope. The same note is then played more loudly. Describe how the trace changes, and how it stays the same.

  • The trace becomes taller, because the amplitude is larger. ✓
  • The number of waves across the screen stays the same, because the frequency (pitch) is unchanged. ✓
04
Analysis
[2 marks]

On the same oscilloscope, a higher-pitched note is now played at the same loudness as before. Describe how this trace differs from the first.

  • More waves fit across the same width of screen, because the frequency is higher. ✓
  • The height of the trace is the same, because the loudness (amplitude) is unchanged. ✓
05
Analysis
[2 marks]

A student writes that increasing the amplitude of a sound makes it higher pitched. Explain what is wrong with this statement.

  • Increasing the amplitude makes the sound louder, not higher pitched. ✓
  • Pitch is changed by the frequency, not the amplitude. ✓

Amplitude to loudness, frequency to pitch. Do not cross the pairs.

06
Diagram
[3 marks]

Two sounds, P and Q, are displayed on the same oscilloscope with identical settings.

P Q
(a) State which sound is louder, and give your reason. [2] (b) State how the pitch of P compares with the pitch of Q. [1]

(a) Q is louder. ✓ Its trace has a larger amplitude (it is taller). ✓

(b) They have the same pitch, because they show the same number of waves across the screen (same frequency). ✓

Q is taller but has the same number of waves, so it is louder at the same pitch.

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.