Colour TheoryMr. Chapman

Science 8

The Visible Spectrum

As we all know by now (I hope!) the visible spectrum of light is all the colours that you can see in the rainbow – ROY G. BIV

Addition of Colour

Mixing colours together to make other colours is known as addition of colour. The primary colours are blue, green and red.

Notice! These are different than the primary colours that we normally talk about for painting.

Addition of Colour

When all three primary colours are added together, they make white light.

Different combinations of the primary colours produce secondary colours.

The secondary colours are magenta, cyan and yellow.

AN AWESOME INVENTION!

TV was an incredible breakthrough. It used tiny pixels that each produced one of three colours: red, blue, or green. How does this allow all of the images that you see on the screen?

Addition of Colour

When all three primary colours are added together, they also produce white light.

Where have you seen the three primary colours before in your everyday life?

Making Secondary Colours

Yellow is produced by mixing red and green.

Magenta is produced by mixing red and blue.

Cyan is produced by mixing green and blue.

The Human Eye!

The human eye has specialized cells that are sensitive to different ranges of colours. These specialized cells are called cones.

There are three types of cones, each sensitive to different ranges of colour: red, green, and blue. When light hits the cones, the cones send messages to your brain.

The colour that you see depends on the type and number of cones responding to the light entering your eye.

Are You Colour Blind?

Some people can not see all the colours; some people are colour- blind.

Their cone cells may be defective, causing them to be yellow and green colour blind or red and green coloured blind.

Look at page 144 of your textbook to find out if you are colour- blind.

SUBTRACTING COLOURS

It gets confusing!

Colour Subtraction

Coloured sunglasses act as filters which take out, or subtract, some part of light. If an object is red, such as an apple, this means that it is reflecting the colour red.

If the apple is reflecting red that means that it is absorbing the two other primary colours, blue and green.

If green and blue are being absorbed that means that they are being subtracted.

Making Sense Of Subtraction

If an object is yellow, this means that it is a combination of red and green. If red and green are being reflected, then blue is being absorbed (subtracted).

If an object is coloured magenta, this means that it is a combination of blue and red, and a subtraction of green.

When all the colours are absorbed we get black. Black is the absence of colour.

Complete the Worksheet In Class!