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Year 7

Travelling sound

I can explain why sounds are quieter at a greater distance, and why sound waves travel faster in solids and liquids than gases but not at all through a vacuum.

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New
New
Year 7

Travelling sound

I can explain why sounds are quieter at a greater distance, and why sound waves travel faster in solids and liquids than gases but not at all through a vacuum.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. Sound spreads out and becomes quieter (lower amplitude vibrations) as it travels.
  2. Sound travels through a medium by vibrations being passed on between the particles of the medium.
  3. Sound travels faster through liquids than gases as the particles are closer so vibrations can be passed on more easily.
  4. Sound travels fastest through solids due to strong attractive forces between particles so many vibrate when one does.
  5. Sound waves are caused by vibrations of particles so sound can't travel through a vacuum (where there are no particles).

Common misconception

Sound needs gaps through which it moves in order to enter a room or space. At the same time, most pupils can state that sound can't travel in a vacuum but the majority cannot correctly explain why.

An alarm can still be heard in a sealed container that has no gaps (e.g. kilner jar). Provide lots of experiences and examples of sound travelling through gases, liquids and solids and struggling to travel through a partial vacuum.

Keywords

  • Particles - What solids, liquids and gases are made up from.

  • Vibrate - To regularly and repeatedly move back and forth.

  • Sound wave - A ‘pulse’ that travels through a material caused by the vibrations of particles.

  • Medium - The material that sound is travelling through, that is set vibrating.

  • Vacuum - An area of space with no matter present (that contains no particles).

To show that sound is not transmitted by a vacuum, a semi-inflated balloon inside a vacuum jar will inflate when air is extracted and burst against a drawing pin fixed to the wall of the container; it will make a tiny sound in contrast to the sound of a balloon popping in the air (Task C).
Teacher tip

Equipment

Balloon, air pump, tubing and suitable valve, bell jar, petroleum jelly (to seal bell jar to its platform), drawing pins or similar sharp object (Task C). Metal objects and string (Task B).

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.
A vibrating object creates a sound. Which of the following correctly describes the amplitude of the vibration?
how high the sound is
the speed of the vibrating object
the number of vibrations per second
Correct answer: the furthest distance the object moves from its original position
Q2.
A vibrating object creates a sound. Which of the following correctly describes the change in the sound heard if the amplitude of the vibration decreases?
The volume of the sound increases.
Correct answer: The volume of the sound decreases.
The pitch of the sound increases.
The pitch of the sound decreases.
Q3.
Which of the following correctly describes the movement of air particles when a sound wave travels through the air?
They are carried along with the sound wave.
Correct answer: They vibrate back and forth and do not travel.
They move away from the source of the sound.
Q4.
Solids, liquids and gases are made of particles. Which of the following describe the arrangement or the movement of particles in a solid?
Correct answer: They are very close together.
They can move around each other.
Correct answer: They are tightly bound to neighbouring particles.
Correct answer: They vibrate around fixed positions.
Q5.
Which of the following describe the arrangement or the movement of particles in a liquid?
Correct answer: They can move around each other.
They are tightly bound to neighbouring particles.
They vibrate around fixed positions.
They are much farther apart than in solids.
Q6.
Which of the following describe the arrangement or the movement of particles in a gas?
Correct answer: They can move around each other.
They vibrate around fixed positions.
They are tightly bound to neighbouring particles.
Correct answer: They are much farther apart than in liquids.

Exit quiz

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6 Questions

Q1.
Which of the following words means ‘a completely empty area of space’?
continuum
vaccine
vacuole
Correct answer: vacuum
vanadium
Q2.
Which of the following words means ‘a substance that a wave travels through’?
small
mean
Correct answer: medium
median
large
Q3.
How many of the following can sound travel through: vacuum, gas, liquid, solid?
none of them
1
2
Correct answer: 3
4
Q4.
Sound travels at different speeds through different states of matter. Starting with the slowest, sort the following states of matter in order of increasing sound speed.
1 - gas
2 - liquid
3 - solid
Q5.
Which of the following explains why sound travels at different speeds through solids, liquids and gases?
Sound waves can travel faster through larger gaps between particles in gases.
Correct answer: Vibrations are passed along faster if particles are bonded together.
Vibrations are passed along faster if the particles can move around each other.
Q6.
A vibrating object creates a sound. Which of the following correctly describes the change in the sound heard the further a sound wave travels?
Correct answer: The sound gets quieter.
The amplitude of particle vibrations increases.
Correct answer: The energy of the sound wave is shared between more particles.
The energy of the sound wave is shared between fewer particles.