Clem Waves Lesson02 Presentation
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Transcript of Clem Waves Lesson02 Presentation
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Waves and Wave PropertiesWaves and Wave Properties
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Why are we able to see?
Answer: Because there is light.
Andwhat is light?
Answer: Light is a wave.
Sowhat is a wave?
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Answer: A wave is a disturbance
that carries energy from place toplace.
A wave does NOT carry matter withit! t ust moves the matter as it goes
through it.
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Some waves do not need matter
(called a medium! to be able tomove ("or e#am$le% through s$ace!.
&hese are called electromagneticwaves(or ' waves!.
Some waves )S& have a mediumin order to move. &hese are called
mechanical waves.
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Wave &y$es
".Transverse waves: Waves in which the mediummoves at right angles to the direction of the wave
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*arts o" transverse waves:
#rest: the highest point of the wave
Trough: the lowest point of the wave
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$. #ompressional %or longitudinal& waves:
Waves in which the medium moves bac' andforth in the same direction as the wave
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*arts o" longitudinal waves:
#ompression: where the particles are close together
(arefaction: where the particles are spread apart
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Wave *ro$erties
Wave properties depend on what
%type of energy& is ma'ing the waves.
".Wavelength: The distance between one point
on a wave and the e)act same place on the
ne)t wave.
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$. *re+uency: ,ow many waves go past a point
in one second- unit of measurement is hert %,&.
The higher the fre+uency/ the more energy in thewave.
"0 waves going past in " second 1 "0 ,
"/000 waves go past in " second 1 "/000 ,
" million waves going past 1 " million ,
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2.Amplitude: ,ow far the medium moves from
rest position %where it is when not moving&.
(emember that for transverse waves/ the highest
point is the crest/ and the lowest point is the trough.
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(emember that for compressional waves/ the
points where the medium is close together are
called compressionsand the areas where themedium is spread apart are called rarefactions.
The closer together and further apart the
particles are/ the larger the amplitude.
com$ression
rare"action
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The energyof a wave is proportional to the
s+uare of its amplitude. 3athematically
spea'ing . . .
4 1 #A$
Where:
4 1 energy %the capacity to do wor'&
# 1 a constant %depends on the medium&
A 1 amplitude
*or e)ample:
f the amplitude is e+ual to 2 units%and we assume # 1 " for this case& . . .
4 1 %"& %2&$1 %"& %5& 1 5 units
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Note that when the amplitude of a wave is one
unit/ the energy is one unit.
6When the amplitude is doubled/ the energy is
+uadrupled.
6When the energy is "0 times greater/ the energy is "00
times greater!
Amplitude Energy
1 1
2 4
3 9
4 165 25
6 36
7 49
8 64
9 81
10 100
4 1 #A$
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7. Wave speed: 8epends on the medium in
which the wave is traveling. t varies in
solids/ li+uids and gases.
A mathematical way to calculate speed:
wave speed 1 wavelength ) fre+uency
%in meters& %in ,&
OR
v + " # ,
Problem: f a wave has a wavelength of $ m and a fre+uency of 900 ,/
what is its speed
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Answer: speed 1 $ m ) 900 , 1 "000 m;s
-hanging Wave irection
".(eflection: When waves bounce off a surface.
f the surface is flat/ the angle at which the wave
hits the surface will be the same as the angle at
which it leaves the surface
%angle in 1 angle out&.
This is the law of reflection.
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$. (efraction: Waves can bend.
This happens when a wave
enters a new medium and its
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2.8iffraction: The bending of waves A(O>N8
an obect.
The amount of bending depends on the sie of
the obstacle and the sie of the waves.
?arge obstacle/ small wavelength 1 low diffraction
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/mage Sources
$007 3icrosoft #orporation/ One 3icrosoft Way/
(edmond/ WA 5@09$B255 >sed with permission.
Tom ,enderson/ The Physics #lassroom
http:;;www.mwit.ac.th;Cphysicslab;appletD07;physicsDcl
assroom;#lass;sound;u""l"c.html
Eraalennest/ Wi'ipedia http:;;en.wi'ipedia.org;wi'i;*ile:#restDtrough.svg