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Auralith Learning

Year 8 · Science · Light and sound · Lesson 1

Sound waves

How sound is made and travels, amplitude and loudness, frequency and pitch, the speed of sound in different materials, and echo calculations.

Whiteboard video lesson: Sound waves

24-minute video lesson

Teaching, worked examples and 20 practice questions solved step by step.

Watch free for a month

What your child will learn

  • Describe sound as a vibration
  • Explain why sound can't travel through a vacuum
  • Link amplitude to loudness and frequency to pitch
  • Compare the speed of sound in solids, liquids and gases
  • Calculate distances using echoes

The method

  1. Sound is made by vibrations and travels as a longitudinal wave through solids, liquids and gases (not a vacuum).
  2. Bigger amplitude means louder; higher frequency (Hz) means higher pitch.
  3. Distance = speed × time; sound is about 340 m/s in air.
  4. For an echo, the sound travels there and back, so halve the total distance.

Key words: vibration, longitudinal wave, amplitude, frequency, hertz, pitch, vacuum, echo, ultrasound.

Worked examples

The first three practice questions from the lesson, with every step.

Question 1

What unit is frequency measured in?

  1. Step 1: Hertz (Hz)
  2. Step 2: 1 Hz = 1 vibration per second

Answer: Hertz (Hz)

Question 2

What does the amplitude of a sound wave tell you?

  1. Step 1: How loud it is
  2. Step 2: Bigger amplitude → louder

Answer: How loud the sound is

Question 3

What does the frequency of a sound wave tell you?

  1. Step 1: Its pitch
  2. Step 2: Higher frequency → higher pitch

Answer: Its pitch