Who this is for: Cambridge IGCSE Coordinated Science (0654) students who want sound — longitudinal waves, pitch, loudness and speed — to become a reliable source of marks instead of a vague wave topic.
What query it owns: how to understand and revise sound in Cambridge IGCSE Coordinated Science.
Why this is safe: this page owns the sound revision-guide angle, while Tutopiya’s Sound subtopic page owns the learning resource and the free Sound quiz owns the practice.

Sound is a longitudinal wave that needs a medium to travel. Cambridge IGCSE Coordinated Science (0654) expects you to describe how sound is produced, relate pitch to frequency and loudness to amplitude, and use v = fλ and distance = speed × time for echo questions. This guide links each idea to the explanation and calculation stems examiners set.

Key takeaways

• Sound is a longitudinal wave — particles vibrate parallel to the direction of travel.
• Sound needs a medium (solid, liquid or gas); it cannot travel through a vacuum.
• Pitch depends on frequency; loudness depends on amplitude.
• Speed of sound in air ≈ 330–340 m/s (use the value given in the question).
• v = fλ links speed, frequency and wavelength for any wave, including sound.

What is sound in Cambridge IGCSE Coordinated Science?

Sound is produced when an object vibrates, setting nearby particles into vibration. These compressions and rarefactions travel as a longitudinal wave through a medium. Unlike light, sound cannot pass through a vacuum because there are no particles to carry the vibration. Understanding how sound differs from transverse waves (like light) is essential for description questions.

You can read the full explanation, diagrams and notes on Tutopiya’s Sound subtopic page before you attempt questions.

Pitch, loudness and the wave equation

Property	Depends on	Effect on wave
Pitch (how high/low)	Frequency (Hz)	Higher frequency → higher pitch
Loudness (how loud/quiet)	Amplitude	Greater amplitude → louder sound
Speed	Medium and temperature	Faster in solids than in gases

Equation	When to use
v = fλ	Link speed, frequency and wavelength
distance = v × t	Echo and reflection-of-sound questions

Example: sound of frequency 500 Hz and wavelength 0.68 m → v = 500 × 0.68 = 340 m/s.

Sound in past-paper wording: command words that matter

Command word / phrase	What the question wants	Typical sound stem
Describe	Say what happens, in order	”Describe how sound travels through air.”
State	One fact, no explanation	”State why sound cannot travel in a vacuum.”
Explain	Cause and effect	”Explain why the pitch of a guitar string increases when it is tightened.”
Calculate	Use v = fλ or distance = vt	”Calculate the wavelength of a 256 Hz note in air.”

Worked exam-style stems (how to answer the wording)

1. “State two differences between sound waves and light waves.” Sound is longitudinal and needs a medium; light is transverse and can travel in a vacuum. Mark-scheme reward: longitudinal vs transverse + medium requirement.
2. “A student hears an echo 0.4 s after clapping. The speed of sound is 340 m/s. Calculate the distance to the reflecting surface.” Distance to surface = ½ × 340 × 0.4 = 68 m (sound travels there and back). Reward: halving the total distance.
3. “Explain why sound travels faster in water than in air.” Particles in water are closer together, so vibrations pass on more quickly. Reward: closer particles → faster transfer.

Test yourself with the Sound quiz once you can describe longitudinal waves, link pitch to frequency and solve echo calculations.

How sound connects to the rest of Coordinated Science physics

Sound builds on General Wave Properties — amplitude, frequency, wavelength and v = fλ — and contrasts with Light (transverse). The Cambridge IGCSE Coordinated Science resource hub links every Properties Of Waves subtopic.

Common mistakes students make

• Saying sound is a transverse wave (it is longitudinal).
• Forgetting to halve the distance in echo questions (sound travels to the wall and back).
• Confusing pitch (frequency) with loudness (amplitude).
• Claiming sound travels faster in gases than in solids (solids are faster).
• Using the wrong speed of sound — always use the value given in the question.

When you need more support

If sound questions keep costing marks, work through the Sound quiz, then get focused help from a Cambridge IGCSE Coordinated Science tutor.

Frequently asked questions

Is sound hard in Coordinated Science? Learn longitudinal vs transverse, pitch/frequency and loudness/amplitude, plus v = fλ and echo maths — that covers most questions.

Why can sound not travel in a vacuum? There are no particles to vibrate and carry the wave; sound needs a medium.

What is the difference between pitch and loudness? Pitch is how high or low a note sounds (depends on frequency); loudness is how loud it sounds (depends on amplitude).

How do I revise sound effectively? Practise descriptions of longitudinal waves, pitch/loudness links and echo calculations, then take the Sound quiz.

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