LIGHT !from bonfires to lasers

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Sources of light

Hot objects give out light.

A bonfire

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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

Light is reflected as a beam and can be seen on the wall.

wall

mirror

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Move the mirror

The light reaches a different place on the wall.

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 - - -

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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

redorang

eyellow green blue indigoviolet

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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 reflection-

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CDs

The surface has tiny pits and smooth bits in a spiral pattern

the pits scatter light from a laser the smooth bits reflect the light so a coded message is read.

spiral

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Laser show

Physics is in everything