Difference between revisions of "Colour"
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Revision as of 08:34, 13 March 2019
Contents
Key Stage 1
Meaning
Colour is something we see with our eyes.
About Colours
The colours we can see are red, orange, yellow, green, blue, indigo and violet. If you mix colours of paint together you can get another colour. Red and yellow paint mixed together makes orange. Blue and yellow paint mixed together make green. Blue and red paint mixed together makes purple. If you mix all three you can make brown.
Examples
Grass is a green colour. | The colour of this rose is red. |
The sky is blue in colour. | I will colour in The Sun yellow with paint. |
Key Stage 3
Meaning
Colour is a property of objects that we can see.
About Colour
White light can be divided into 7 colours:
- Red
- Orange
- Yellow
- Green
- Blue
- Indigo
- Violet
- Red light has the lowest frequency and the longest wavelength.
- Violet light has the highest frequency and the shortest wavelength.
Colour and Objects
A red object reflects red light but absorbs all the others colours. | A blue object reflects blue light but absorbs all the others colours. |
Eyes and Colour
- The human eyes only have three different colour sensing cells called cones. They can detect; red, green or blue light. All other colours we see are caused by a pair of different cones detecting light at the same time.
- If the red cones and blue cones both detect light then we see magenta.
- If the red cones and green cones both detect light then we see yellow.
- If the blue cones and green cones both detect light then we see cyan.
Coloured Mixing
Primary Colours
Secondary Colours
Colour Filters
Through a red filter: |
Through a blue filter: |
Through a green filter: |
Through a yellow filter: |
Through a cyan filter: |
Through a magenta filter: |
Key Stage 4
Meaning
Colour is a property of objects that we can see.
About Colour
White light can be divided into 7 colours:
- Red
- Orange
- Yellow
- Green
- Blue
- Indigo
- Violet
- Red light has the lowest frequency and the longest wavelength.
- Violet light has the highest frequency and the shortest wavelength.
- An object may appear to have a colour for three reasons:
- Reflection - An object may reflect some frequencies while absorbing others.
- Filtering - An object may be viewed through a transparent medium which absorbs certain frequencies of light.
- Scattering - An object may be viewed through a transparent medium which scatters certain frequencies of light. This is why the sky appears blue and the Sun appears yellow.
Eyes and Colour
- The human eyes only have three different colour sensing cells called cones. They can detect; red, green or blue light. All other colours we see are caused by a pair of different cones detecting light at the same time.
- If the red cones and blue cones both detect light then we see magenta.
- If the red cones and green cones both detect light then we see yellow.
- If the blue cones and green cones both detect light then we see cyan.
Coloured Mixing
Additive Colours
- The additive primary colours are Red, Blue and Green. This means when two colours of light are added, they make new colours.
Colour and Reflection
A red object reflects red light but absorbs all the others colours. | A blue object reflects blue light but absorbs all the others colours. |
- Colour exists because objects absorb some frequencies of light while other colours are not.
- A coloured object absorbs some colours and reflects others. For example leaves are green because the chlorophyll inside them absorbs red and blue light but not green.
Light Colour | Object Colour | Appearance |
Red | Red | Red |
Blue | Black | |
Green | Black | |
Magenta | Red | |
Cyan | Black | |
Yellow | Red | |
Blue | Red | Black |
Blue | Blue | |
Green | Black | |
Magenta | Blue | |
Cyan | Blue | |
Yellow | Black | |
Green | Red | Black |
Blue | Black | |
Green | Green | |
Magenta | Black | |
Cyan | Green | |
Yellow | Green | |
Magenta | Red | Red |
Blue | Blue | |
Green | Black | |
Magenta | Magenta | |
Cyan | Blue | |
Yellow | Red | |
Cyan | Red | Black |
Blue | Blue | |
Green | Green | |
Magenta | Blue | |
Cyan | Cyan | |
Yellow | Green | |
Yellow | Red | Red |
Blue | Black | |
Green | Green | |
Magenta | Red | |
Cyan | Green | |
Yellow | Yellow |
Colour Filters
A red filter only transmits red light but absorbs all the others colours. | A blue filter only transmits blue light but absorbs all the others colours. |
- Colour filters work by absorbing some frequencies of light while transmitting others.
- Looking through a colour filter makes any object whose colour is absorbed appear black.
Colour Filter | Object Colour | Appearance |
Red | Red | Red |
Blue | Black | |
Green | Black | |
Magenta | Red | |
Cyan | Black | |
Yellow | Red | |
Blue | Red | Black |
Blue | Blue | |
Green | Black | |
Magenta | Blue | |
Cyan | Blue | |
Yellow | Black | |
Green | Red | Black |
Blue | Black | |
Green | Green | |
Magenta | Black | |
Cyan | Green | |
Yellow | Green | |
Magenta | Red | Red |
Blue | Blue | |
Green | Black | |
Magenta | Magenta | |
Cyan | Blue | |
Yellow | Red | |
Cyan | Red | Black |
Blue | Blue | |
Green | Green | |
Magenta | Blue | |
Cyan | Cyan | |
Yellow | Green | |
Yellow | Red | Red |
Blue | Black | |
Green | Green | |
Magenta | Red | |
Cyan | Green | |
Yellow | Yellow |