1. What are the colours of a rainbow?

2. Ray diagram review WWW EBI
I have labelled all rays and angles correctly
I have labelled most rays and angles correctly
I have drawn correct direction arrows on all my rays
I have drawn the normal at 90
I have drawn diagrams with a pencil and ruler
I need to make sure I label all rays and angle correctly
I need to draw correct direction arrows on all the rays
I need to use a pencil when drawing diagrams
I need to make sure I measure all angles carefully

3. Dispersion Success Criteria Today you will:
State what happens when light passes through a prism
Explain why different colours are refracted through different angles
Describe how rainbows are created

4. Know that light is dispersed when it shines through a prism
What happens when light meets a boundary between air and glass?
It refracts.
glass
air
Why does it refract?
Light travels at different speeds in different materials:
– light travels more slowly in glass than air
– the inside of the ray slows down before the outside
- so the light bends.

5. Know that light is dispersed when it shines through a prism
What will happens when light is shone through a prism?
The light is split :
it is dispersed.
Dispersion: when light splits into separate colours.

6. Understand that different colours are refracted through different angles
How does a prism split light into different colours?
Copy the diagram into your book and add the labels
ray box prism normal angle of incidence screen

7. Understand that different colours are refracted through different angles
How does a prism split light into different colours?
Set up the equipment as shown in your diagram
Move the incident ray until you see the best spectrum on the screen – measure this angle of incidence.
Record the colours you can see on the screen

8. Ray diagram review – part 2
WWW
EBI
I have labelled all rays and angles correctly
I have labelled most rays and angles correctly
I have drawn correct direction arrows on all my rays
I have drawn the normal at 90
I have drawn diagrams with a pencil and ruler
I need to make sure I label all rays and angle correctly
I need to draw correct direction arrows on all the rays
I need to use a pencil when drawing diagrams
I need to make sure I measure all angles carefully

9. Understand that different colours are refracted through different angles

10. Richard Of York Gave Battle In Vain
Understand that different colours are refracted through different angles
Red
Orange
Yellow
Green
Blue
Indigo
Violet
The colours that make up white light are called the spectrum. The order of the colours in the spectrum is always the same,
because different colours are refracted by different angles.
Richard Of York Gave Battle In Vain

11. Be able to explain how rainbows are created
What conditions are needed for a rainbow to be created?
How does this create a rainbow?
Rain
+ Sun

12. Be able to explain how rainbows are created
Your friend has sent you a postcard saying that they have seen a rainbow on holiday, but they don’t understand how this happens. Write a postcard back explaining how a rainbow is created…
raindrops
speed
refraction/ refracted
sunlight
dispersion/ dispersed
angle

13. Be able to explain how rainbows are created
We see light from the Sun as white light…
When sunlight shines through raindrops,
…its speed changes –
the light slows down.
This causes the light to be refracted.
Different colours are refracted at different angles,
…so the light is dispersed.
We see the dispersed colours as a rainbow.

14. Final challenge!