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→Key Stage 3
===About Sound===
: [[Sound]] is a [[Longitudinal Wave|longitudinal wave]] because the direction of [[vibration]] of the [[particle]]s is [[parallel]] to the direction of motion of the [[wave]].
: [[Sound]] is caused by [[object]]s [[Vibration|vibrating]]. The [[vibration]] is then passed through a [[medium]] as a [[wave]] of [[compression]].
: [[Sound]] is transmitted by [[particle]]s colliding with one another.
: [[Sound]] is [[Absorb (physics)|absorbed]] by soft [[material]]s.
: [[Absorb (physics)|Absorbing]] [[sound]]s is useful in ear defenders and [[sound]] studios where it is important to reduce the [[sound]] that gets past.
==Key Stage 4==
===Meaning===
[[Sound]] is a [[longitudinal]] [[wave]] of [[Compression Wave|compression]] and [[rarefaction]] that [[Energy Transfer|transfers energy]] and [[information]] through a [[medium]].
===About Sound===
: [[Sound]] is a [[Longitudinal Wave|longitudinal wave]] because the direction of [[vibration]] of the [[particle]]s is [[parallel]] to the direction of motion of the [[wave]].
: [[Sound]] is caused by [[object]]s [[Vibration|vibrating]]. The [[vibration]] is then passed through a [[medium]] as a [[wave]] of [[compression]] and [[rarefaction]].
: [[Sound]] is transmitted due to [[particle]]s colliding with one another.
: The [[speed]] of [[sound]] through [[air]] is 340[[m/s]].
{| class="wikitable"
|-
|[[File:LongitudinalWave.gif|center]]
|-
| style="height:20px; width:200px; text-align:center;" |This is animation shows how [[sound]] travels along a [[material]] through the [[collision]] of [[particle]]s with one another.
|}
{| class="wikitable"
|-
| style="height:20px; width:200px; text-align:center;" |'''Sound Waves'''
|-
|[[File:VibrateSound1.gif|center]]
|-
| style="height:20px; width:200px; text-align:center;" |This animation shows a [[speaker]] creating a [[sound]] by making a [[wave]] of [[Compression Wave|compression]] (dark grey) that passes through the [[air]].
|}
===Medium===
: [[Sound]] [[wave]]s can pass through [[solid]]s, [[liquid]]s and [[gas]]es but [[sound]] cannot pass through a [[vacuum]].
: [[Sound]] travels fastest through a [[solid]] because the [[particle]]s are already touching so they have little distance to travel to pass on the [[vibration]].
: [[Sound]] travels the slowest through a [[gas]] because the [[particle]]s in a [[gas]] are spread far apart so they take some time before they [[collide]] with the next [[particle]] to pass on the [[vibration]].
{| class="wikitable"
|-
|[[File:ParticleModelSolidLiquidGas.png|center|500px]]
|-
| style="height:20px; width:200px; text-align:center;" |A [[diagram]] showing the '''particle model''' for [[solid]]s, [[liquid]]s and [[gas]]es.
|}
===Interface between Media===
: When [[sound]] meets the [[interface]] between two [[medium|media]] it can be [[transmitted]] (and [[refracted]]), [[reflected]] or [[Absorb (Physics)|absorbed]].
: When [[sound]] is [[transmitted]] from one [[medium]] into another it changes [[speed]] and [[wavelength]] but it's [[frequency]] remains constant. The change in [[Wave Speed|wave speed]] causes [[refraction]] in which the [[wave]] changes direction. - This is used in [[Ultrasound Imaging]].
: When [[sound]] is [[reflected]] form a surface this is because the difference between density of the two [[media]] is large. The [[sound]] bounces off the [[interface]] following the [[Law of Reflection|law of reflection]] and is heard as an [[echo]]. - This is used in [[Echo Location]] and [[Ultrasound Imaging]].
: When [[sound]] is [[Absorb (Physics)|absorbed]] the [[energy]] is [[Energy Transfer|transferred]] into the [[Thermal Energy Store|thermal energy store]] of a [[material]]. - This is used in is ear defenders and [[sound]] studios where it is important to reduce the [[sound]] that gets past an [[interface]].
===Sound Volume===
: The [[Volume (Sound)|volume]] of a [[sound]] is how loud or quiet it is.
: [[Volume (Sound)|Volume]] is determined by the [[amplitude]] of the [[wave]] the maximum [[displacement]] of the [[wave]] from its [[Equilibrium Position|equilibrium position]].
{| class="wikitable"
|+ [[Longitudinal Wave]]s cannot be easily pictured so they are represented by [[Transverse Wave]]s on an [[Oscilloscope]] screen.
|-
|[[File:OscilloscopeScreen4.png|center|200px]]
|[[File:OscilloscopeScreen5.png|center|200px]]
|[[File:OscilloscopeScreen6.png|center|200px]]
|-
| style="height:20px; width:200px; text-align:center;" |This is a high [[amplitude]] wave showing a [[sound]] with a high [[Volume (Sound)|volume]], so it is loud.
| style="height:20px; width:200px; text-align:center;" |
| style="height:20px; width:200px; text-align:center;" |This is a low [[amplitude]] wave showing a [[sound]] with a low [[Volume (Sound)|volume]] so it is quiet.
|}
===Pitch===
: A [[sound]] can be a high [[pitch]] or low [[pitch]].
: Pitch is determined by the [[frequency]] of the [[wave]] (how quickly the wave [[Vibration|vibrates]]).
: The [[frequency]] of a [[sound]] [[wave]] is [[measure]]s in [[Hertz]] ([[Hz]]).
{| class="wikitable"
|+ [[Longitudinal Wave]]s cannot be easily pictured so they are represented by [[Transverse Wave]]s on an [[Oscilloscope]] screen.
|-
|[[File:OscilloscopeScreen1.png|center|200px]]
|[[File:OscilloscopeScreen2.png|center|200px]]
|[[File:OscilloscopeScreen3.png|center|200px]]
|-
| style="height:20px; width:200px; text-align:center;" |This is a low [[frequency]] wave showing a [[sound]] with a low pitch, so it is a deep [[sound]].
| style="height:20px; width:200px; text-align:center;" |
| style="height:20px; width:200px; text-align:center;" |This is a high [[frequency]] [[wave]] showing a [[sound]] with a high [[pitch]].
|}