TOPIC 4.3

SNC2P

Lesson Goals

Today we will learn that:colours of light can be added together to form a variety of

colours through two investigations.Pigments can subtract colours from light.

WWW.POLLEVERYWHERE.COM WHAT COLOURS DID YOU

OBSERVE IN YESTERDAY’S ACTIVITY?

IF YOUR HAVE A CELL PHONE, PLEASE TAKE IT OUT NOW ... ITS TIME TO TEXT IN YOUR OBSERVATIONS!

TEXT YOUR RESPONSES TO ... 37607

ACTIVITY 4.4 RESULTS (Textbook P.300)

OBSERVATIONSFILTER

COLOURS ACTIVITY 4.4: TRICKING THE EYE ACTIVITY: SUNLIGHT & PADDLE COLOURS

RED RED RED

GREEN GREEN GREEN

BLUE BLUE BLUERED + GREEN YELLOWYELLOW

RED + BLUE MAGENTA (PURPLE) GREEN +

BLUE CYAN (TURQUOISE)

RED + BLUE + GREEN WHITE

Did you know ...That the millions of colours on a computer monitor

or TV screen are produced with ONLY ...

3COLOURS!!

Recognizing ColoursYour eyes have only 3 types of cells that can

recognize millions of colours.When you observe a colour, it is because different

combinations of these cells are stimulated.A TV screen uses a system of only three colours to

create the effect of many different colours, just like the cells in your eyes.

Primary ColoursPRIMARY COLOURS:

Three colours that can be combined to create any other colour.

Can be additive or subtractive.

RED GREEN BLUE

Additive Primary ColoursADDITIVE PRIMARY COLOURS ARE:

RedGreenBlue

These three colours of light are also known as primary colours.

Additive Primary ColoursCreating different colours of light depend on the

additive colour theory.

When all 3 primary colours are combined, they make white light.

Additive Secondary ColoursBy combining only two of the

primary colours, you will make a secondary colour.

These are:YellowCyanMagenta

Complementary ColoursColours that are directly

across from each other are complementary colours.Red & cyanGreen & magentaBlue & yellow

Pigments can subtract colour from light

When an object absorbs a colour, it removes (or subtracts) it from the beam of light. The colours of most of the objects that you observe every day are the result of subtracting colours.

There are three subtractive primary colours: cyan, magenta, and yellow. A variety of combinations of these three colours can subtract light from white light to produce nearly any colour.

Magenta, cyan, and yellow films subtracting colours from white light. What do you see when these three overlap?

The colours produced by subtracting equal amounts of two of the three subtractive primary colours are called subtractive secondary colours.

The subtractive secondary colours are the same as the three additive primary colours (red, green, and blue).

When the three subtractive primary colours are added together and subtracted from white light, you get black. The “code” for black is K so as not to be confused with blue.

Subtractive Colour Theory of LightIf a colour is absorbed, it will not make it

to your eye. You only see the reflected colours.

Paint and pigment manufacturers mix all three of the primary subtractive colours in varying degrees to make any range of colours reflect from a surface.

Primary pigments

Yellow Magenta Cyan Black

Colour Wheel

The COLOUR WHEEL shows how all the colours are related.

Copyright © 2010 McGraw-Hill Ryerson Ltd.

Tertiary colours are formed by mixing the secondary colours. The resulting colours are yellow-green, orange, crimson, cobalt, and turquoise.

Colour Wheel

Copyright © 2010 McGraw-Hill Ryerson Ltd.

The subtractive primary colours cyan, magenta, and yellow are the same as the additive secondary colours.

Colour Wheel Relationships

Copyright © 2010 McGraw-Hill Ryerson Ltd.

The additive primary colours red, green, and blue are the same as the subtractive secondary colours.

Colour Wheel Relationships

Copyright © 2010 McGraw-Hill Ryerson Ltd.

The colours that are directly across from each other on the colour wheel are complementary colours.

When you add complementary colours, the result is white.

When you subtract complementary colours, the result is black.

Colour Wheel Relationships

Copyright © 2010 McGraw-Hill Ryerson Ltd.

Diagrams can be used to show how colours are subtracted from white light when it hits a film of a certain colour.

Using Diagrams to Illustrate Subtractive Colours

ACTIVITY 4.6 (Textbook P.301)SUBTRACTING COLOUR WITH FILMS & WITH YOUR EYESTHREE parts to the activity.Part A:

At stations.Please record your observations on your handout.

Part B:At your desk in groups of 2 or 3.Pg. 301 “What To Do”. Do # 6 and 7.Please record your observations on your handout.

Part C:Answer the questions on the handout.

HAND-IN YOUR ACTIVITY HANDOUT AT THE END OF CLASS.

HOMEWORK: Handouts on Addition & Subtractive Colours

STATION 1 - YELLOWPlace the YELLOW film over the colour wheel

found on page 299 of the textbook.Beside each colour on your list (see handout),

write the colour that it appears to be after the YELLOW film was placed over it.

Go to the next colour stationThere are 4 colour stations to complete.

STATION 2 - REDPlace the RED film over the colour wheel

found on page 299 of the textbook.Beside each colour on your list (see handout),

write the colour that it appears to be after the RED film was placed over it.

Go to the next colour stationThere are 4 colour stations to complete.

STATION 3 - ORANGEPlace the ORANGE film over the colour wheel

found on page 299 of the textbook.Beside each colour on your list (see handout),

write the colour that it appears to be after the ORANGE film was placed over it.

Go to the next colour stationThere are 4 colour stations to complete.

STATION 4 - GREENPlace the GREEN paddle over the colour

wheel found on page 299 of the textbook.Beside each colour on your list (see handout),

write the colour that it appears to be after the GREEN paddle was placed over it.

Go to the next colour stationThere are 4 colour stations to complete.