The amplitude of a sound wave determines its

Step 1: Analyze the question The question asks which property of a sound wave is determined by its amplitude.

Step 2: Explain the concept Amplitude is the maximum displacement of particles in the medium from their rest position. It tells us how much energy the wave carries.

Here is how the main properties of sound link to wave features:

• Loudness depends on amplitude. A bigger amplitude means more energy and a louder sound.
• Pitch depends on frequency. A higher frequency gives a higher pitch.
• Quality (timbre) depends on the waveform shape, which comes from the mix of overtones or harmonics. It lets us tell a guitar from a piano playing the same note.
• Frequency is the number of vibrations per second (in hertz). It is a property of the source, not something amplitude decides.

Step 3: Work through the options

• A. Frequency: incorrect. Frequency is determined by the rate of vibration of the source.
• B. Quality: incorrect. Quality depends on the overtones present.
• C. Loudness: correct. Greater amplitude means greater intensity, which we hear as a louder sound.
• D. Pitch: incorrect. Pitch is determined by frequency.

Step 4: Answer The amplitude of a sound wave determines its loudness, which is option C.

Exam tip: Remember "Amplitude → Loudness" (both are about "how much"), and "Frequency → Pitch" (both are about "how high"). Quality (timbre) is about the "type" of sound, shaped by its overtones.