Dispersion and Colour

Date

Lesson Outcomes How I did Targets

Task 1:

Describe how white light is split

Level 5

Task 2:

Use a prism to separate

white light Level 6

Task 3:

Explain the appearance of coloured objects in coloured lights.

Level 7

Connector

What is a rainbow, how is it made?

What are the colours of the rainbow?

BIG picture

• What skills will you be developing this lesson?

• PLTs Creative thinkers, effective participators.

• Numeracy skills: measure angles using a protractor and analyse their results for patterns.

• History link: Science in history

Bending Light

Glass makes light bend – but it doesn’t bend every colour the same amount.

Blue light bends the most and red light bends the least.

Green light is somewhere in the middle.

Bending White Light

White light gives a very surprising result.

The glass prism bends the light – and shows a complete rainbow of colours.

This tells us that white light is really a mixture of different colours.

The rainbow of colours is called a spectrum.

DispersionA prism splits a ray of white light into a spectrum of colours.

This is known as dispersion.

When white light is split, the colours always follow the same order.

Use this phrase to remember the order of colours:

Richard Of York Gave Battle In Vain

Task 1: (Level 5)Task 1: Copy down the statements below and say if they

are true or false. If they are false, explain why!

1. White light is made up of 10 colours.

2. Violet light is refracted more than any other colour of visible light in the spectrum.

3. A spectrum is a spread of colours.

4. Prisms put colour into light.

5. Indigo is a dark pink colour.

True or false?

FALSE

TRUE

TRUE

FALSE

FALSE

Task 1 (Level 5)• Task 1:

• Make up a phrase to help you remember the colours of the rainbow.

• ROYGBIV (4 mins)

Keywords for Task 1:

• red

• orange

• yellow

•Green

•Blue

•Indigo

•violet

Task 1: Review

Lesson Outcomes How I did Targets

Task 1:

Level 5

Met?

Partly met?

Not met?

How can I improve on task 1?

Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column.

Seeing Things!

You see a non-luminous object when light hits the object and is then reflected into your eyes.

So how do we see different colours?

Why does a red dress look red?

Why does a green apple look green?

How do you see non-luminous objects such as a book?

Seeing Red

Why does a red snooker ball look red in white light?

White light is made up of a spectrum of colours.

The snooker ball absorbs all the colours of the spectrum except red.

Only red light is reflected into your eye, so the snooker ball appears red.

Seeing Green

Why does a green snooker ball look green in white light?

The snooker ball absorbs all the colours of the spectrum except green.

Only green light is reflected into your eye, so the snooker ball appears green.

Seeing Black

Why does a black snooker ball look black in white light?

The snooker ball absorbs all the colours of the spectrum.

No light is reflected into your eye, so the snooker ball appears black.

Seeing White

Why does a snooker ball look in white light?

The snooker ball does not absorb any of the colours of the spectrum.

The whole spectrum of light is reflected into your eye, so the snooker ball appears white.

Seeing MagentaWhy does a magenta ball look magenta in white light?

The snooker ball absorbs all the colours of the spectrum except red and blue.

Red and blue light are reflected into your eye, so the snooker ball appears magenta.

Seeing Different Colours

What colours are absorbed by this frog’s skin?

This part of the skin absorbs all the colours of the spectrum except red, and so reflects red light.

This part of the skin absorbs all the colours of the spectrum and none are reflected.

New information task 2

Task 2 (Level 6)• Task 2: • Ray box, prisms, metal plate,

plain paper, power pack• Set up the equipment as shown

in the diagram• Use the colouring pencils to

reproduce the image onto he paper

• Make sure the amount of colour is also shown

Keywords for Task 2:

• refraction

• prism

• ray

• light

•rainbow

Task 2: Extension

• Which colour of light was bent most by the prism?

• The colour of light that was bent the most was………………..

• Which colour of light was bent least by the prism?

• The colour that was bent the least was……..• Identify seven colours in the experiment and

write down the order that they appear in the spectrum.

• Why can you not see brown?• You cannot see brown because…………..

Task 2: Answers

• The colour of light that was bent the most was violet

• The colour that was bent the least was red

• Red, orange, yellow, green, blue, indigo, violet

• You cannot see brown because it is not a colour of the spectrum it is a mixture of colours

Task 2: Review

Lesson Outcomes How I did Targets

Task 2:

Level 6

Met?

Partly met?

Not met?

How can I improve on task 2?

Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column.

FiltersA red filter absorbs all colours…

A blue filter absorbs all colours…

A green filter absorbs all colours...

…apart from red light.

…apart from blue light.

…apart from green light.

FiltersA magenta filter absorbs all colours…

A cyan filter absorbs all colours…

A yellow filter absorbs all colours...

…apart from red and blue.

…apart from green and blue.

…apart from red and green.

Seeing in Coloured Light

Why do colours look different in different coloured light?

Consider a red ball in red light.

The red light shines on the ball.

The red ball reflects the red light and so appears red.

Seeing in Coloured Light

What colour does a red ball appear in green light?

The green light shines on the ball.

The red ball only reflects red light and so it absorbs the green light.

So in green light, this ball does not reflect any light and so appears black.

Task 3: (Level 6)

Object Colour of lightColour object seems to be

Red socks

Red

Blue

Green

Blue teddy

Red

Blue

Green

Green camel

Red

Blue

Green

Magenta book

Red

Blue

Green

Red

Black

Black

Black

Blue

Black

Black

Black

Green

Red

Blue

Black

Task 3 (Level 7)• Look at the variety of objects

in the tray• Write down the colour of each

one on the table of results• Apply the blue filter• Record the colour• Apply the red filter• Record the colour• Animation 6.5 Go Science

Keywords for Task 3:

• light

•Colour

•Ray

•Reflect

•Absorb

•filter

Results

Object Colour in white light

Colour with red filter

Colour with blue filter

Task 3: Review

Lesson Outcomes How I did Targets

Task 3:

Level 6

Met?

Partly met?

Not met?

How can I improve on task 3?

Go back to your lesson outcome grid and fill out the ‘How I did’ and the ‘Targets’ column.

Review of lesson