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What is the Subtractive Mixing of Colours?
Grade Level:
Class 6
Space Technology, EVs, Climate Change, Biotechnology, HealthTech, Robotics, Chemistry, Physics
Definition
What is it?
Subtractive mixing of colours is what happens when you mix different coloured paints or inks. Each pigment absorbs (or 'subtracts') certain colours of light and reflects others. When you mix them, more light is absorbed, making the resulting colour darker.
Simple Example
Quick Example
Imagine you have a red paint and a yellow paint. If you mix them, you get orange. The red paint absorbs blue and green light, reflecting red. The yellow paint absorbs blue light, reflecting yellow and green. When mixed, they absorb even more light, and only orange light is reflected, making the mixture appear orange.
Worked Example
Step-by-Step
Let's see how mixing primary colours of paint works:
Step 1: Start with Yellow paint. It reflects Yellow, Green, and Red light, absorbing Blue.
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Step 2: Take Magenta paint. It reflects Magenta (Red + Blue) light, absorbing Green.
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Step 3: Mix Yellow and Magenta paints together. Both paints will absorb the colours they normally absorb.
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Step 4: Yellow paint absorbs Blue. Magenta paint absorbs Green.
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Step 5: When mixed, the Yellow and Magenta paints together absorb both Blue and Green light. The only colour left to be reflected is Red.
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Answer: Mixing Yellow and Magenta paints gives you Red paint.
Why It Matters
Understanding colour mixing is crucial in many fields. It's used by graphic designers creating posters, by artists painting murals, and even in printing newspapers and books. This knowledge helps engineers design better displays and predict how materials will look under different lights.
Common Mistakes
MISTAKE: Thinking that mixing all primary colours of paint makes white light. | CORRECTION: Mixing all primary colours of paint (Cyan, Magenta, Yellow) actually makes black or a very dark brown, because almost all light is absorbed.
MISTAKE: Confusing subtractive mixing (paints) with additive mixing (lights). | CORRECTION: Subtractive mixing uses pigments and makes colours darker. Additive mixing uses coloured lights and makes colours brighter, eventually leading to white light.
MISTAKE: Believing that Red, Green, and Blue are the primary colours for paints. | CORRECTION: The primary colours for subtractive mixing (paints/inks) are Cyan, Magenta, and Yellow (CMY). Red, Green, Blue (RGB) are primary colours for additive mixing (lights).
Practice Questions
Try It Yourself
QUESTION: If you mix Cyan paint and Yellow paint, what colour will you get? | ANSWER: Green
QUESTION: Why does mixing more colours in subtractive mixing usually result in a darker colour? | ANSWER: Because each additional pigment absorbs more light, leaving less light to be reflected.
QUESTION: You have a set of CMY (Cyan, Magenta, Yellow) paints. Which two colours would you mix to get Blue? | ANSWER: Cyan and Magenta
MCQ
Quick Quiz
Which of the following is an example of subtractive colour mixing?
Mixing red and green spotlights to make yellow light
Mixing blue and yellow paints to make green paint
The colours on a TV screen
Sunlight passing through a prism
The Correct Answer Is:
B
Subtractive mixing involves pigments like paints, where colours get darker when mixed. Option B is the only example involving mixing paints. Other options are about light or light separation.
Real World Connection
In the Real World
When you get a colourful printout from your school's printer or see a vibrant advertisement banner, it's all thanks to subtractive mixing. Printers use Cyan, Magenta, Yellow, and Black (CMYK) inks. Each tiny dot of ink subtracts specific colours of light, creating all the beautiful shades you see on paper.
Key Vocabulary
Key Terms
PIGMENT: A material that changes the colour of reflected or transmitted light as a result of wavelength-selective absorption. | ABSORB: To take in light and not reflect it. | REFLECT: To bounce back light from a surface. | PRIMARY COLOURS (Subtractive): Cyan, Magenta, and Yellow (CMY) are the basic colours that, when mixed, can create a wide range of other colours. | SECONDARY COLOURS (Subtractive): Colours formed by mixing two primary subtractive colours, e.g., Red, Green, Blue.
What's Next
What to Learn Next
Now that you understand how paints mix, next you can learn about 'Additive Mixing of Colours'. This will show you how coloured lights combine, which is very different from mixing paints and helps you understand how screens work!
