Download pdf - 13 Wave Behaviour

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WAVE BEHAVIOURTOPIC 13 : GENERAL WAVE PROPERTIES

PreparedbyCgEdnaMariaHjOsman.E-ma

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1Monday, February 21, 2011
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WAVE BEHAVIOURSimple wave behaviour can be observed using a

Ripple Tank

Ripple Tank

Avibratingdipper,shallowglass-bottomedtray,

alightsourcedirectlyoverthetrayanda

whitescreenbelow. PreparedbyCgEdnaMariaHjOsman.E-ma

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WAVE BEHAVIOURRipple Tanks can create:

Plane Wavefronts Circular Wavefronts

These wavefronts are used to observe wave behaviours.

PreparedbyCgEdnaMariaHjOsman.E-mail:[email protected]



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WAVE BEHAVIOURAny wave can behave in the following ways:

Reflected Refracted DiffractedPreparedbyCgEdnaMariaHjOsman.E-mail:[email protected]



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REFLECTION OF WAVESWhen a wave hits a solid barrier / obstacle it will be

bounced outwards in the opposite direction.




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REFLECTION OF WAVESFocus : Reflection of plane waves on straight barriers.

Wavefrontshitting at an angle

Wavefronts hittingstraight on




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CONSTRUCTION OF REFLECTED

WAVESDraw the line representing the direction of

wave travel 90 degrees to the wavefronts

and hitting the reflecting surface.

Incident

Wavefronts

Incident Point PreparedbyCgEdnaMariaHjOsman.E-mail:[email protected]



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WAVES

Use the protractor to create a normal line

at the incident point.

Incident Point

Normal




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WAVES

Use the protractor to measure

the angle between the normal

and the incident line.

Angle

Normal

Incident Line C




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WAVES

This angle is known

as the incident angle

or angle of incidence

Angle

Normal

Incident Line C

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WAVES

AngleNormal

Incident Line

Use the protractor to measure put and mark the same sizeangle at

the incident point but away the from the normal.

Incident Point

C

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WAVES

ReflectedLineNormal

Incident Line

C

Angle

This angle between thenormal and the reflected

line is known as the

reflected angle or angle of

reflection

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WAVES

Use a ruler to measure the distance between one wavefront to the

next immediate wavefront. This is the wavelength.

Wavelength

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WAVES

Mark these wavelengths consecutively on the reflected line starting

from the incident point.

Incident PointPreparedbyCg




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WAVES

Draw straight lines 90degrees to the reflected

line, on the wavelength

marks to construct the

reflected wavefronts.

ReflectedWavefronts

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REFLECTED WAVES

Angle of

Incidence

Angle of

Reflection=

Wavelength remains constant

Speed remains constant

Frequency remains constant

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REFRACTION OF WAVESThe change in the direction of the wave as they move

from one medium to another.

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REFRACTION OF WAVESThe depth of the medium / substance the waves pass

through will also affect the waves.

Water @depth A

Water @depth B

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REFRACTION OF WATER WAVESWavefronts will be affected as follows when moving

from deep area to shallow area.

ShallowDeep

The wavefronts passes through the different depths straight on.

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ShallowDeepWavelength

longerin deep area

Wavelength

shorterin shallow area

The wavelengthdecreases as it moves from deep to shallow area.

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ShallowDeepSpeed

fasterin deep area

Speed

slowerin shallow area

The speeddecreases as it moves from deep to shallow area.

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ShallowDeep

The wavefronts passes through the different depths at an angle.

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REFRACTION OF WATER WAVES

Describe the visible changes found here!

ShallowDeep

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Direction of wave travel changes !

Deep

Shallow

Wave path is refracted towards the normal line.

Refracted wave path

Original wave path

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Wavelength also changes !

Incident wavelength is longer than the refracted wavelength

Deep

Shallow

Refracted wavelength

Incident wavelength

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Deep

ShallowWave path is refracted

towards the normal.

Thewavelengthdecreases.

Thespeeddecreases.

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from shallow area to deep area.

DeepShallow

The wavefronts passes through the different depths straight on.

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DeepShallowWavelength

longerin deep area

Wavelength

shorter

in shallow area

The wavelength increases as it moves from shallow to deep area.

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DeepShallow

The wavefronts passes through the different depths at an angle.

PreparedbyCg


ail:edna.maria.osman@gma

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REFRACTION OF WATER WAVESDirection of wave travel changes !

Deep

Shallow

Wave path is refracted away from the normal line.

Refracted wave path

Original wave path

PreparedbyCgEdnaMariaHjOsman.E-m


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Deep

Shallow

Incident wavelength is smaller than the refracted wavelength

Refracted wavelength

Incident wavelength

Wavelength also changes !



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Deep

Shallow

Wave path is refracted

away from the normal.

Thewavelengthincreases.

Thespeedincreases.



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CONSTRUCTION OF REFRACTED WAVES

Deep

Shallow

Plane wave passing

through straight on.

Scenario A Scenario B

Plane wave passing

through at an angle. PreparedbyCgEdnaMariaHjOsman.E-m


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Draw the line representingthe direction of wave travel

90 degrees to the wavefronts

and hitting the surface.

Deep

Shallow

Scenario A



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Use a ruler to measure the

distance between one

wavefront to the next

immediate wavefront.

This is the wavelength.

Wavelength

Deep

Shallow

Scenario A



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Wavelength

Deep

Shallow

Shallow to Deep : TheWavelengthincreases.

Longer

WavelengthCreate longer wavelengths

for wavefronts in deep area

Scenario A



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Deep

Shallow

Markthese new longer wavelengths consecutively on the line of

travel starting from the incident point.

Incident Point

Scenario A



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Deep

Shallow

Draw straight lines 90 degrees to the line of travel, on the

wavelength marks to construct the refracted wavefronts.

Scenario A



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Deep

Shallow

Scenario B

Plane wave passing

through at an angle. PreparedbyCgEdnaMariaHjOsman.E-m


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DeepShallow

Scenario B

Shallow to Deep : Wave path is refracted away from the normal.

Create the refracted wave path

from the point of incident.

IncidentPoint





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DeepShallow

Scenario B

Shallow to Deep : TheWavelengthincreases.

Wavelength

Longer

WavelengthCreate longer wavelengths

for wavefronts in deep area





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DeepShallow

Scenario B

Markthese new longer wavelengths consecutively on the line of

travel starting from the incident point.

IncidentPoint





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DeepShallow

Scenario B

Draw straight lines 90 degrees to the line of travel, on the

wavelength marks to construct the refracted wavefronts.

PreparedbyC

gEdnaMariaHjOsman.E-m



C O O S


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Deep

Shallow

Wave path is refracted

away from the normal.

Thewavelengthincreases.

Thespeedincreases.

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Deep

ShallowWave path is refracted

towards the normal.

Thewavelengthdecreases.

Thespeeddecreases.

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SUMMARY OF WAVE BEHAVIOUR

Wavelength

Speed

REFLECTION REFRACTION

Wavelength

Speed

Direction

Angle ofIncidence

Angle ofReflection=

INCREASE /

DECREASECONSTANT

TOWARDS / AWAYFROM NORMAL

DEPENDS ON DEPTH OF MEDIUM

PreparedbyC

