Sound waves

Lesson objectives

state that:sound cannot travel through a vacuum but can travel through solids, liquidsand gases

describe how sounds travel through solids, liquids and gases

explain in terms of the particle model why sound needs a medium.

explain how sound travels at different speeds in different types of material

explain everyday phenomena in terms of the different speeds at which sound travelsin air and solidsKey words:

vibrations , molecules, medium, vacuum, solid, liquid,

gas, longitudinal, wavelength

Sound waves

Sound can travel through solids, I know this because …………………………..……………………………………………….………………………………………………….

Sound can travel through liquids, I know this because …………………………..………………………………………………….………………………………………………….

Sound can travel through gases, I know this because …………………………..………………………………………………….………………………………………………….

Sound waves

In a sound wave the molecules vibrate backwards and forwards

CC

C

R R R

Compression;air molecules are squashed together

Rarefaction;air molecules are further apart

Sound waves

speaker cone

vibrates.

Sound waves spread like ripples on

a pond.

Airmolecule

Sound waves

Sound waves

Sound waves

If you listen carefully you might.Explain how!

Can you hear a space craft explode in space or on the moon?

Explain!

P 3 2.6 SOUND

For a C grade you should be able to:• State the range of hearing for a typical human.• Describe the properties of a sound wave, including its longitudinal nature.• Describe the behaviour of a sound wave, including reflection and refraction.

For an a grade you should also be able to:• Explain why mechanical vibrations produce sound waves.

Mechanical waves

electromagnetic waves

electromagnetic waves

Mechanical waves

electromagnetic waves

Mechanical waves

Mechanical waves

electromagnetic waves

Reflecting sound

Echoes

Hard, flat surface

Soft, absorbing surface

Uneven surface