Light
travels in
straight lines.
Light travels very, very fast!

Guess how long it takes for light to
come from the SUN to the Earth.

8 years
 8 days
 8 hours
 8 minutes
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It takes
8 minutes
for light to reach us from the Sun!
Light travels 300 000 kilometres through space every second!
That’s the same as 300,000,000m/s.
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Shadows

Light travels in a straight line.

If something gets in its path the light is
blocked.
A shadow is formed and has a magnified
size compared to the object that creates
it.

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Sun
Shadows

How do
they form?
Use Rays.
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6
We can make magnified
shadows !
- by blocking out the light.
Changing positions varies the size of the shadow.
If the object is close to the lamp,
the shadow gets larger.
If the objects is close to the screen,
the shadow gets smaller.
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The Earth is a sphere
The Sun cannot shine on both sides of the
Earth at the same time



Some of the Earth is bright - day
Some is dark – night
The Earth rotates so each part has day
and night.
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Day and night
Daylight in the UK
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your notes.
Dusk in
India
Dark in
China
Light from the Sun
Light
Dark
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At midday in Africa
It is dawn in Ontario
 It is dusk in India

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your notes.
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As the Earth spins
the position of the Sun varies.



Morning – the sun rises - it is light.
The Sun gets higher in the sky.
Then the Sun sinks and sets.
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Shadows move during the day

Watch the shadow of the stick
 to tell the time
 like a sundial.
stick
6.00 pm
6.00 am
12.00
noon
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The Moon
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The Moon
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your notes.

The Moon is not a source of light.

Light from the Sun shines on the Moon. Some light is
reflected so we see it on Earth.
Light from
the Sun

The Moon takes about
28 days to move round the Earth.

It always shows Earth the same side.

The shape we see changes
during the 28 days- a lunar month.
MOON
EARTH
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The Moon travels round the Earth
half MOON or
first quarter
new
Moon
Sunlight
no Moon
is seen
Earth
full
Moon
last
quarter
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your notes.
The Moon
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your notes.

The Moon is very much smaller than the
Sun.

But the Moon is very much closer than
the Sun.

They both look the same size in the sky.
eye
Moon
Sun
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your notes.
Sometimes the Sun does not
shine during the day.

Even when it is not cloudy!

Let’s perform a simulation.
NASA
 Shut
one eye
 Use your thumb to represent the Moon so that
you cannot see the Sun.
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Sun
18
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your notes.
An eclipse of the Sun




Sun
When the Moon stops the light from the Sun
reaching the Earth
We call it an eclipse.
During an eclipse, it goes dark in the middle of
the day.
An eclipse of the Sun is rare
and happens at a new Moon.
Moon
Earth
Moon
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your notes.
A partial eclipse
is when the Moon
does not cover all
of the Sun.
Sun
This happens
much more often
than a total
eclipse.
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your notes.
An Eclipse of the Moon


Full Moon: the Earth is between the Moon and the Sun.
Light gets to the Moon because they are not in line.
1
2
sunlight
3
Earth’s shadow
4



The Earth sometimes blocks out the sunlight from reaching the
Moon.
Then we cannot see the Moon (in position 3).
This is an eclipse of the Moon.
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What have we learned?
(Sunlight takes 8 minutes to reach the Earth.)
1.
2.
3.
4.
5.
Shadows form when light is blocked out.
We can tell the time by shadows.
The moon reflects light to the Earth.
Its shape changes because of shadows.
Eclipses happen when light is blocked out.
6. - Light
travels in straight lines!
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Pinhole Camera
tinfoil
Greaseproof paper
Tin can
One small hole
in the foil
Point the foil end at a Bunsen or candle
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Pinhole camera ray diagram
dobject
dimage
hobject
himage
The image has four specific properties,
Important:
Size: Magnification (larger in this case)
S-A-L-T
Attitude: inverted (upside down)
“d” is for distance
Location: Focused on the screen
“h” is for height
Type: real (it can be projected onto a screen)
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