You can explain the difference between point sources and big lightsources
You can explain what causes half and full shadows
You are familliar with the concepts of divergent, convergent and parallal lightbeams
You can explain lunar and solar eclips
You can replicate lunar and solar eclipses using a drawing
You can explain the different phases of the moon
You can explain why we have different seasons
You can explain the difference in lightintensity during different seasons
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Schadow
Slide 4 - Woordweb
In the early days when there were no computers, smartphones or other high-tec gadgets, people did find a way to enjoy themselves using light and shadow. Oldfashioned and boring? Perhaps, but we make use of it even now and people are still enjoying the playfull way we use light and shadow together.
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Schadow
"Schaduw comes to life if the light of a lightsource is wholy or partially blocked by an object. A precondition for having shadows is that you need a lightsource and a blocking object.
Furthermore, you can differentiate in the kind of lightsources which can be divided into natural lightsources (like the sun) and artificial lightsources (like a man made lamp).
wikipedia
poem
Slide 9 - Tekstslide
Light and shadow
You need light to see shadows
Light rays travel in straight lines
Schadows exist in places
were light is blocked
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Different kind of lightbeams
Divergent lightbeam: Lightrays move away from each other
They seem to orginate from one point
Parallel lightbeams: Lichtrays stay at equal distance
Convergent lichtbeam:
Lightrays are focussed on one point
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Pointsource or Large lightsource
pointsource
A pointsource is a lightsource for which assume that all light originates from a very small point. In reality this often is not the case since most lightsources are most of the time bigger than a small point of light.
big lightsource
If the lightsource is very big, the object will receive light from multiple angles which results in different shadows.
Slide 12 - Tekstslide
Different kinds of shadows
Half shadow (penumbra): A shadow which still receives partial light of the lightsource
Full schadow (umbra): A shadow which receives no light at all
Workingspaces are better for working if you do not have a lot of sharp shadows. Therefore we make use of large fluorescent tubes.
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Peculiar schadows
Where are the lightsources?
A stadium needs a lot of light to make all shadows dissapear
Nice how a shadow give you another look at things
Would this be during the day or at night?
Why do you think so?
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Slide 15 - Video
This is how red, green and blue mix
Click on the picture for an overview
Colored light sources will provide nice shadows
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Blue sky
Sun& solar eclipses
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Why is the sky blue?
Watch the video and make a note
about why the sky is blue
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The moon will be in different phases during a month. This has to do with the orbit of the moon around the earth and how the moon is situated to both the earth and the sun.
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Slide 20 - Video
Corona
another word for the circel around the sun during a solar eclips
but now famous
for something
completely
different
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Slide 22 - Video
explanation
The sun is very big in relation to the earth.
Therefore you do not draw it like a point source.
And if you do not have a point source you will get full and half shadows.
Slide 23 - Tekstslide
explanation
This picture makes clear that when the sun is shining at an angle (which especially is the case during winter time), the liughtintensity is far less because the same amount of light is spread over a larger distance.
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Seasons
The axis of the earth is always at an angle relative to the sun.
Because of this summer and winter will take turns with each other on the northern and southern halves of the earth.
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Slide 26 - Video
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A couple of colors is prjected onto a screen.
Drag the colors to the right spot
Black
Green
Yellow
White
Magenta
Blue
White
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Who is nearest to the screen?
A
The girl
B
The mother
Slide 30 - Quizvraag
Slide 31 - Video
Where do you find a halfshadow?
A
B
C
A
A
B
B
C
C
Slide 32 - Quizvraag
Explain to me why the color of the sky is blue?
Slide 33 - Open vraag
Why can we see light?
A
reflection
B
diffusion
C
parallel
D
dispersion
Slide 34 - Quizvraag
At the spot where you see a halfshadow, there is no light
A
True
B
Not true
Slide 35 - Quizvraag
You cannot see light rays
A
True
B
Not true
Slide 36 - Quizvraag
The shadow of an object is bigger than the object itself with a divergent lightbeam.
Keep in mind that light has wave like properties. Because of this, light can bend around a corner when it goes through a very narrow opening. You do not have to remember this, this is more something for higher education. But it is nice to know that strange things can happen.