Waves
PropertiesofWaves
●Wavestransferenergy.
●Wavesmaybeeithertransverseorlongitudinal.Candidatesshouldunderstandthatina
transversewavetheoscillationsareperpendiculartothedirectionofenergytransfer.Ina
longitudinalwavetheoscillationsareparalleltothedirectionofenergytransfer.
●Electromagneticwavesaretransverse,soundwavesarelongitudinalandmechanical
wavesmaybeeithertransverseorlongitudinal.
●Longitudinalwavesshowareasofcompressionandrarefaction.
●Thetermsfrequency,wavelengthandamplitude.
●Allwavesobeythewaveequation:
v=fxλ
visspeedinmetrespersecond,m/s
fisfrequencyinhertz,Hz
λiswavelengthinmetres,m
Candidatesarenotrequiredtorecallthevalueofthespeedofelectromagneticwaves
throughavacuum.
Refraction
●Thenormalisaconstructionlineperpendiculartothereflectingsurfaceatthepointof
incidence.
●Wavesundergoachangeofdirectionwhentheyarerefractedataninterface.Wavesare
notrefractediftravellingalongthenormal.Snell’slawandthereasonwhywavesare
refractedarenotrequired.
Reflection
●Theangleofincidenceisequaltotheangleofreflection.
●Theimageproducedinaplanemirrorisvirtual.Candidateswillbeexpectedtobeableto
constructraydiagrams.
Diffraction
●Wavescanbereflected,refractedanddiffracted.Candidatesshouldappreciatethat
significantdiffractiononlyoccurswhenthewavelengthofthewaveisofthesameorderof
magnitudeasthesizeofthegaporobstacle.
Sound
●Soundwavesarelongitudinalwavesandcausevibrationsinamedium,whichare
detectedassound.Soundislimitedtohumanhearingandnodetailsofthestructureofthe
eararerequired.
●Thepitchofasoundisdeterminedbyitsfrequencyandloudnessbyitsamplitude.
●Echoesarereflectionsofsounds.
Properties of Waves
All waves transfer ______________________________________________
Waves are created by ______________________________________________________________________________________
There are two types of waves; transverse and longitudinal.
In a transverse wave the oscillations are _______________________________________ to the direction that the wave travels in.
In a longitudinal wave the oscillations are _______________________________________ to the direction that the wave travels in.
Examples of transverse waves are ____________________________________________________________________________
________________________________________________________________________________________________________
Examples of longitudinal waves are ___________________________________________________________________________
________________________________________________________________________________________________________
The diagram below is an example of a ____________________________________________ wave.
The diagram below is an example of a ____________________________________________ wave.
What do the following terms mean? Add them to the appropriate diagram above (if possible).
Peak ___________________________________________________________________________________________________
Trough __________________________________________________________________________________________________
Compression _____________________________________________________________________________________________
Rarefaction ______________________________________________________________________________________________
Wavelength ______________________________________________________________________________________________
Amplitude _______________________________________________________________________________________________
Frequency _______________________________________________________________________________________________
Wave speed _____________________________________________________________________________________________
𝑣 = 𝑓×𝜆
Symbol
Quantity
Units
Unit Symbol
v
f
λ
Rearrange the equation to make f and then λ the subject.
Complete this table by calculating the missing values.
v
f
3
8
336
40
340
300 000 000
λ
1.2
0.015
0.8
0.8
850
500 000 000
The diagram shows waves being
produced on a rope. The waves are not
reflected by the wall.
Draw an arrow on the diagram to show
the direction in which the waves transfer
energy.
Which of the labelled arrows show the:
Amplitude?
__________
Wavelength?
__________
State which type of wave is shown in the diagram and explain how you can tell?
________________________________________________________________________________________________________
________________________________________________________________________________________________________
The diagram shows two ways in which a
wave can travel along a slinky spring.
Clearly indicate and label the
wavelength of Wave A and Wave B
Which a longitudinal wave?
_______
Which is a transverse wave? _______
Refraction
Explain what the word refraction means.
________________________________________________________________________________________________________
________________________________________________________________________________________________________
A student investigated the refraction of light as it passed out of a clear plastic
block into the air. The diagram shows the apparatus the student used.
What name is given to the dashed line? ____________________________
The angle i is the ______________________________________________
Use the letter r to mark the angle of refraction on the diagram.
Which piece of equipment would you use to measure the angles?
____________________________________________________________
Why doesn’t the light ray bend when it enters the plastic block?
____________________________________________________________
Why does the light ray bend when it travels from the plastic block to the air?
________________________________________________________________________________________________________
________________________________________________________________________________________________________
The two diagrams, A and B, show a light ray travelling into a glass block.
Complete the diagrams to show the paths that the light rays take as they enter and then leave the glass block.
In diagram A, when the light ray travels from air to glass it will bend _________________________________________ the normal.
In diagram A, when the light ray travels from glass to air it will bend _________________________________________ the normal.
Reflection
When dealing with light and mirrors it is important to use the correct vocabulary. Explain what the following words mean when used
to describe an image produced through a lens.
Inverted _________________________________________ Upright _________________________________________________
Magnified ________________________________________ Diminished ______________________________________________
Real ____________________________________________ Virtual __________________________________________________
The diagram shows a ray of light from a ray box that is reflected by a plane mirror. What name is given to the dashed line labelled
as J?
_________________________________________________________
What is the name given to K?
_________________________________________________________
What is the name given to L?
_________________________________________________________
If K was doubled what would happen to L?
________________________________________________________
If K was halved what would happen to L?
________________________________________________________
A student looking into the mirror can see an image of the ray box.
Which words from the list at the top of this page can be used to describe the image that the student sees?
________________________________________________________________________________________________________
What is the law of reflection?
________________________________________________________________________________________________________
The diagram shows a model used to demonstrate an illusion known as ‘Pepper’s Ghost’.
A small light bulb and thin sheet of glass are put inside a box. The thin sheet of glass acts as a mirror. Although the light bulb is
switched on, a student looking into the box cannot see the bulb. What the student does see is a virtual image of the bulb.
Use a ruler to complete a ray diagram to show how the image of the light bulb is formed. Mark and label the position of the image.
The image seen by the student is virtual. Why?
________________________________________________________________________________________________________
Diffraction
Explain what the word diffraction means.
________________________________________________________________________________________________________
________________________________________________________________________________________________________
The diagrams show water waves in a ripple tank moving towards a gap in a barrier.
The water waves diffract as they pass through the gap. Complete the diagrams to show the diffracted water waves.
Diffraction happens the most when the wavelength of the wave is ____________________________________________________
________________________________________________________________________________________________________
Terrestrial television does not use satellites. Terrestrial television signals and radio signals both use radio waves.
Radio signals are transmitted at a longer wavelength than terrestrial television signals.
In hilly areas it may be possible to receive radio signals but not receive terrestrial television signals. Explain why.
________________________________________________________________________________________________________
________________________________________________________________________________________________________
________________________________________________________________________________________________________
________________________________________________________________________________________________________
Sound
How are sounds produced?
________________________________________________________________________________________________________
________________________________________________________________________________________________________
How do drums produce sound? _____________________________________________________________________________
How to guitars produce sound? _____________________________________________________________________________
How do flutes produce sound?
_____________________________________________________________________________
Sound waves are longitudinal waves; use the diagram of a longitudinal wave to explain how sound waves travel from a speaker to
an ear.
________________________________________________________________________________________________________
________________________________________________________________________________________________________
________________________________________________________________________________________________________
What is a vacuum?
________________________________________________________________________________________________________
________________________________________________________________________________________________________
Explain why sound waves cannot travel through a vacuum.
________________________________________________________________________________________________________
________________________________________________________________________________________________________
The diagram shows the apparatus a teacher uses to demonstrate that sound can be reflected.
Using a ruler, draw on the diagram to show how sound from the loudspeaker is reflected by the sheet of metal to the sound sensor.
What is the name given to the reflection of a sound? ______________________________________________________________
The teacher replaced the sheet of metal with a sheet of glass. When he did this, the reading on the sound level meter went down.
Suggest why.
________________________________________________________________________________________________________
________________________________________________________________________________________________________
The amplitude of a wave determines the ___________________________________________ of a wave.
The frequency of a wave determines the ___________________________________________ of a wave.
If a microphone is connected to an oscilloscope it will display the waveforms of different sounds like in the diagrams below
Which of the waveforms has the largest amplitude? _______
Which of the waveforms has the smallest amplitude? _______
Which of the waveforms has the highest frequency? _______
Which of the waveforms has the lowest frequency? _______
How would the sound that made waveform B be like compared to the sound that made waveform D?
________________________________________________________________________________________________________
How would the sound that made waveform C be like compared to the sound that made waveform A?
________________________________________________________________________________________________________
The diagrams show oscilloscope traces for the same musical note played on two different instruments. The oscilloscope settings
are not changed.
How can you tell, from the diagrams, that it is the same musical note?
________________________________________________________________________________________________________
________________________________________________________________________________________________________
How can you tell, from the diagrams, that the musical note has been played on different instruments?
________________________________________________________________________________________________________
________________________________________________________________________________________________________
The EM Spectrum
All electromagnetic waves transfer energy but do not transfer ________________________________________
Complete the table by writing the initials of the waves of the EM spectrum and colours of the visible section into the correct boxes.
Visible Light
X
G
R
Y
As we go from left to right in the table above the wavelength of the waves ___________________________________________
As we go from left to right in the table above the frequency of the waves
___________________________________________
As we go from left to right in the table above the energy of the waves
___________________________________________
As we go from left to right in the table above the speed of the waves
___________________________________________
Circle the correct values for the range of wavelengths of the electromagnetic spectrum.
The longest EM wavelength is around
1015m
104m
10m
The shortest EM wavelength is around
10-6 m
106m
10m
10-4m
10-15m
Complete this table by calculating the missing values. Give your answers to 2 decimal place.
EM Wave
Frequency (Hz)
Infrared
3.2 x 1013
Radio Waves
2.5 x 102
Microwaves
Use
Sending a text from a
mobile phone
Taking a photograph of
a tree
Killing cancerous cells
inside a patient
Turning off a television
with a remote control
Broadcasting a movie
by satellite
In sunbeds to give a
sun tan
Taking a thermal
photograph of a human
Wavelength (m)
1.8 x 109
EM Wave
Use
To sterilise surgical
equipment
A medical tracer
injected into a patient
Security ink used to
mark your property
Producing shadow
images of bones
Broadcasting a local
radio show
Turning a piece of
bread into toast
Cooking food in a
microwave oven
EM Wave
What are the possible risks involved to human health in using a mobile phone?
________________________________________________________________________________________________________
________________________________________________________________________________________________________
________________________________________________________________________________________________________
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