LIGHT !
from bonfires to lasers
Sources of light
A bonfire

Hot objects give out light.
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The Sun

Sunset in Venice
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Stars

Stars and
galaxies
give out
light.
Picture: Liverpool Telescope
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Lightning
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A worm living in dark caves
sends out light from its tail.

Liquid
droplets form
a string of
shining beads
to attract
insects.
tail of worm
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Some cold things give out light:
some fungi
 glow worms
 light sticks
 LEDs
 ‘glow-in-the-dark’
stickers

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How do we see light sources?


Light travels from a
source to our eyes.
We can see sources in
a dark room.
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Can we see in the dark?

If there is no light
 we

cannot see anything!
Let’s try a test–
 Put
a few small objects into the black bag-----
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How do we see things that are
not sources of light?

Light bounces off
and some reaches our eyes.
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On the look out!

How do you
know that
the baby
squirrel
watches as
it feeds?
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Reflection

When light bounces off something
 we

say the light is reflected.
We can try this with
 rough
surfaces
 and shiny surfaces.
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Shiny surfaces
wall
mirror
Light is reflected as a beam and
can be seen on the wall.
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Move the mirror
wall
The light reaches a different
place on the wall.
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Look in a mirror

Light is reflected.

You can see a reflection.
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Change
the
direction
of the
light
beam


Light is still reflected.
You see a reflection
- in a different
direction.
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Multiple
reflections


The lamp hangs
between two large
mirrors on
opposite walls.
The reflection in
the first mirror is
reflected in the
second mirror,
which is reflected
again in the first
mirror - - 18
Now for
some
games!
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Colour
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Sunlight shining on CDs

Where do the
colours come from?
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Rainbow
red
orange
yellow
green
blue
indigo
violet
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Colours

White light is made up
of lots of colours
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Colours from white light
Look at a lamp
through the grating.


You will see
colours.
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
red
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
blue
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Adding colours
with light

This is different to adding paints
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Red + Blue
 magenta
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Blue + Green

cyan
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Green
+ Red
 yellow
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yellow
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magenta
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cyan
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Fairy lights
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Uses

Lasers- produce very bright beams
of light.
 The
atoms all give out their light
together

CDs use laser light
 and
reflection37
CDs

The surface has tiny pits and smooth bits
 in



spiral
a spiral pattern
the pits scatter light from a laser
the smooth bits reflect the light
so a coded message is read.
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Laser show

Physics is in everything
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