Light Targets To know about the colours of light
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Light
TargetsTo know about the colours of light
Dispersion• Each of the colours has a slightly different?
They each have a different wavelength [].
The Light Spectrum
• White light is not made up of just one colour, it is a mixture of all the seven colours of the rainbow – red, orange, yellow, green, blue, indigo and violet.
• This is called the light light spectrumspectrum.
Notes
The light spectrum• If white light travels through
a glass prism the waves are bent – some colours change speed and therefore direction more than others – this splits up light into all its colours
• A second prism will turn the coloured light back to white light
Notes
Applications of the spectrum
The rainbow – light travelling through rainbows is refracted and dispersed to give rainbow.
Primary ColoursYou can make any colour by mixing three
colours. Do you know what they are?
Red Green
Blue
The colours labelled in black text are the PRIMARY COLOURS.
The colours labelled in blue text are called SECONDARY COLOURS. They can be
made by mixing the
primary colours
Cyan
Yellow
Magenta
Primary ColoursPRIMARY COLOURS are RED, GREEN and BLUE
SECONDARY COLOURS are YELLOW, CYAN and MAGENTA
W
Red objectsWhy does a red snooker ball look red in white light?
Remember white light is made of a spectrum
of colours.
The snooker ball absorbs all the colours of the
spectrum EXCEPT red, red light is reflected into our eye. The snooker ball
appears red.
Black objects
Why does a black snooker ball look
black in white light?
The snooker ball absorbs all the colours of the spectrum. NO light is
reflected into our eye. The snooker ball appears
black.
White objects
Why does a white snooker ball look
white in white light?
The snooker ball doesn’t absorb any of the colours
of the spectrum. The whole spectrum of light is
reflected into our eye. The snooker ball appears
white.
Red, blue and green filters
Red filters absorb all colours….
Blue filters absorb all colours….
Green filters absorb all colours….
… apart from red light
… apart from blue light
… apart from green light
PRISMSDispersion of white light
PRISMSSingle coloured light (Red)
PRISMSSingle coloured light (Blue)
COLOURED OBJECTSWhite object in white light
All colours reflected
White objects reflect all colours and absorb none
Object appears white
COLOURED OBJECTSWhite object in blue light
Blue light reflected
White objects reflect all colours and absorb none
Object appears blue
OBJECTS IN COLOURED LIGHTWhite object in red light
Red light is reflected
White objects reflect all colours and absorb none
Object appears Red
OBJECTS IN COLOURED LIGHTRed object in red light
Red is reflected
Red Objects reflect red light
Object appears Red
OBJECTS IN COLOURED LIGHTRed object in blue light
No light is reflected
Red Objects reflect red light and absorb all others
Object appears black
A red apple A green pear
A white plate
THE FRUIT BOWL IN WHITE LIGHT
A red apple A green pear
A white plate
THE FRUIT BOWL IN RED LIGHT
A red apple A green pear
A white plate
THE FRUIT BOWL IN BLUE LIGHT
FILTERS white light – red filter
FILTERS white light – blue filter
FILTERS blue light – blue filter
FILTERS blue light – red filter
FILTERS white light – red and blue filter
How we see colours
• Coloured object reflect one colour and absorb all other colours.
• White objects reflect all colours of the rainbow.
• Black objects absorb all colours and reflect none
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What colour is it?
• Coloured object have a specific colour because they absorb some colours and reflect others.
What colour is it?
• This picture shows why grass is green.
• So the red post box on green grass looks like this
What colour is it?
• How does the post box on the green grass look in red light?
What colour is it?
• How does the red post box on the green grass look in green light?
TESTING COLOUR TESTING COLOUR BLINDNESS. WHAT DO BLINDNESS. WHAT DO YOU SEE?YOU SEE?
TESTING COLOUR TESTING COLOUR BLINDNESS. WHAT DO BLINDNESS. WHAT DO YOU SEE?YOU SEE?
TESTING COLOUR TESTING COLOUR BLINDNESS. WHAT DO BLINDNESS. WHAT DO YOU SEE?YOU SEE?
TESTING COLOUR TESTING COLOUR BLINDNESS. WHAT DO BLINDNESS. WHAT DO YOU SEE?YOU SEE?
TESTING COLOUR TESTING COLOUR BLINDNESS. WHAT DO BLINDNESS. WHAT DO YOU SEE?YOU SEE?
TESTING COLOUR TESTING COLOUR BLINDNESS. WHAT DO BLINDNESS. WHAT DO YOU SEE?YOU SEE?
TESTING COLOUR TESTING COLOUR BLINDNESS. WHAT DO BLINDNESS. WHAT DO YOU SEE?YOU SEE?
Key words
• Spectrum• Reflection• Transmission• Filters• Absorption• Refracted• Dispersed
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