Clem Waves Lesson02 Presentation

7/25/2019 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

Clem Waves Lesson02 Presentation

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