representing waves. there are two ways we can represent a wave in a graph;
TRANSCRIPT
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Representing waves
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Representing waves
There are two ways we can represent a wave in a graph;
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Displacement/time graph
This looks at the movement of one point of the wave over a period of time
1
Time s
-1
-2
0.1 0.2 0.3 0.4
displacement
cm
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Displacement/time graph
This looks at the movement of one point of the wave over a period of time
1
Time s
-1
-2
0.1 0.2 0.3 0.4
displacement
cm
PERIOD
![Page 5: Representing waves. There are two ways we can represent a wave in a graph;](https://reader035.vdocument.in/reader035/viewer/2022062511/551bdd14550346be588b5bb4/html5/thumbnails/5.jpg)
Displacement/time graph
This looks at the movement of one point of the wave over a period of time
1
Time s
-1
-2
0.1 0.2 0.3 0.4
displacement
cm
PERIOD
![Page 6: Representing waves. There are two ways we can represent a wave in a graph;](https://reader035.vdocument.in/reader035/viewer/2022062511/551bdd14550346be588b5bb4/html5/thumbnails/6.jpg)
Displacement/time graph
This looks at the movement of one point of the wave over a period of time
1
Time s
-1
-2
0.1 0.2 0.3 0.4
displacement
cm
PERIOD
IMPORTANT NOTE: This wave could be either transverse or longitudnal
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Displacement/distance graph
This is a “snapshot” of the wave at a particular moment
1
Distance cm
-1
-2
0.4 0.8 1.2 1.6
displacement
cm
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Displacement/distance graph
This is a “snapshot” of the wave at a particular moment
1
Distance cm
-1
-2
0.4 0.8 1.2 1.6
displacement
cm
WAVELENGTH
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Displacement/distance graph
This is a “snapshot” of the wave at a particular moment
1
Distance cm
-1
-2
0.4 0.8 1.2 1.6
displacement
cm
WAVELENGTH
![Page 10: Representing waves. There are two ways we can represent a wave in a graph;](https://reader035.vdocument.in/reader035/viewer/2022062511/551bdd14550346be588b5bb4/html5/thumbnails/10.jpg)
Displacement/distance graph
This is a “snapshot” of the wave at a particular moment
1
Distance cm
-1
-2
0.4 0.8 1.2 1.6
displacement
cm
WAVELENGTH
IMPORTANT NOTE: This wave could also be either transverse or longitudnal
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Wave intensity
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Wave intensity
This is defined as the amount of energy per unit time flowing through unit area
It is normally measured in W.m-2
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Wave intensity
For example, imagine a window with an area of 1m2. If one joule of light energy flows through that window every second we say the light intensity is 1 W.m-2.
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Intensity at a distance from a light source
I = P/4πd2
where d is the distance from the light source (in m) and P is the power of the light source(in W)
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Intensity at a distance from a light source
I = P/4πd2
d
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Sound intensity
The lowest intensity that can normally be heard by a human ear is 1 x 10-12 W.m-2
This is a sound intensity level of 0 dB
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Intensity and amplitude
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Intensity and amplitude
The intensity of a wave is proportional to the square of its amplitude
I α a2
(or I = ka2)
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Intensity and amplitude
This means if you double the amplitude of a wave, its intensity quadruples!
I = ka2
If amplitude = 2a, new intensity = k(2a)2 new intensity = 4ka2
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Surfers know this!
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Let’s try some more questions!