Colour Grade 9

Post on 06-May-2015

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Preview of a PowerPoint show to teach Color to Grade 9 students. Full presentation available from www.warnescience.net

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For FULL presentation click HERE >> www.warnescience.net

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Colour

K Warne

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Waves Revision

Frequency (f) = Waves

time

Period (T)= time

waves

Wavelength () = length of one full wave (distance between any two points in phase)

A wave is a series of pulses or disturbances in a medium.

A Transverse wave has the disturbance is at 90o to the direction of

movement.

c = f .

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Wave Speed

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Wave Speed

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• Long wavelength

• Faster through dense media

Colour & Frequency

• Short wavelength

• Slower through dense media

Low f Faster

High f

Slower

R O Y G B I V

INCREASING FREQUENCY

The Spectrum

R

O

Y

G

B

I

V

Light rays travel slower through glass. The light is

................. (bent) because it strikes the surface at

an angle.

The different colours of light are

caused by different ..........................

of light. Each frequency travels at a different speed through glass and so are

refracted different amounts - that causes the frequencies to be ............

....... This is also known as .......................

The blue end of the spectrum slows down more than the red.

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Vision

We see objects when light reflected off the objects falls on the light sensitive organ at the back of our eyes – the ........................

Different ......................... of light are interpreted by our brains as different COLOURS.

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Vision

We see objects when light reflected off the objects falls on the light sensitive organ at the back of our eyes – the RETINA.

Different FREQUENCIES of light are interpreted by our brains as different COLOURS.

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Colour Perception

Images of living human retinas showing the wide diversity of number of cones ……………….. to …………………………... (Photo credit: University of Rochester)

Web doc

Colour Mixing

Colour Mixing

Colour ADDITION - Light

Primary Colours:

R, G & B

Complementary Colours:

R & Cy

M & G

Y & B

Colour Mixing – SUBTRACTION

PigmentsSubtractive Primary Colours:

Y, Cy & M

Colour pigments (Absorption of light):

Y + M = R

Cy + R = B

Y + Cy = G

Y + M + Cy = B

Selective Reflection

• Opaque objects - light does not pass through them.

• The color of opaque objects is dependant on the colors that are absorbed.

Cyan Magenta Yellow

White

• White is seen when ........................ primary colors are

reflected

Black

• Black is seen when all three primary colors are

absorbed.

Blue

• BLue is seen when ........... and ............... are absorbed.

Blue (in white light)

Blue

• BLue is seen when red and Green are absorbed.

Blue (in white light)

Black

• Black is seen when blue is shone onto .......or .......... (because ........ and ........... are absorbed)

Green (in white light) Red (in white light)Green (in white light) BLACK IN BLUE Red (in white light) BLACK IN BLUE

Transparent Objects

• Red is seen when red is transmitted ( green & blue absorbed).

Transparent Objects

• Yellow is seen when all blue light absorbed (red & green

transmitted).

Selective Absorption

Object absorbs Object reflects Object appears

Red Green and blue Cyan

Green Red and blue Magenta

Blue Red and green Yellow

Red and blue Green Green

Red and green Blue Blue

Blue and green Red Red

Red, blue and green None Black

None Red, green and blue White

Colour MixingLight Colour Object Colour

(white light)

Observed colour

Blue Blue

G, R, Y

Blue

G, R, Y (Black)

Green G

R, B, M

G

R, B, M (Black)

Red R

B, G, Cy

R

B, G, Cy (Black)

Magenta B, R, Y B, R, Y

Cyan R, M, B R, M, B

Yellow R, B, Cy R, B, Cy

ROYGBIV

Same order!

How a rainbow is formed?

<<

How a rainbow is formed?

ROYGBIV

Same order!

Colour Problems1. When monochromatic light passes through glass its frequency

changes. T/F ?? (2)

2. Cut glass is used to make ornaments. In light, it shows all the colours of

the rainbow. Which ONE of the following is NOT an explanation for

this observation?

A White light consists of a spectrum of colours.

B Each colour in white light is refracted by different amounts in glass.

C Cut glass has its own characteristic colours.

D White light splits into colours of different frequencies as it passes through glass.

(3)

3.

More Colour Problems4.

Hi -

This is a SAMPLE presentation only.

My FULL presentations, which contain a lot more more slides and other resources, are freely

available on my resource sharing website:

www.warnescience.net(click on link or logo)

Have a look and enjoy!

WarneScience