1. Describe as fully as you can the difference between the two sounds.
Can you make the noise? (wish I hadn’t asked already!) 1 2 3 4 5
Time (s)
Displacement (m) 1 2 3 4 5
Time (s)
Displacement (m)

2. By the end of this lesson you should be able to…
Learning Objectives
By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.

3. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
The pitch of a note is a result of its frequency.
The higher the frequency (more waves passing a point per second) the higher pitched the note.
low pitch sound
high pitch sound

4. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
Consider the noise from a motorbike moving away from you
Youtube clip of motorbike
Demo with buzzer on string

5. Teacher notes
This four-stage animation explains the Doppler effect using sound.

6. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
The Doppler Effect A B B A
Source of waves is moving to the right
Source of waves is stationary
A hears a sound with a longer wavelength (low pitch). B hears a sound with a shorter wavelength (high pitch)
A and B hear the same sound

7. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
As a car approaches us the sound waves are _________ together. We hear _____ waves per second and so the frequency is greater (_______ pitch).
As a car moves away the sound waves are ________ out. We hear less waves per second and so the frequency is lower (_______ pitch).

8. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
The Doppler Effect is easily audible in sound, particularly if the movement is fast.
The Doppler Effect is also visible in water, again more so if the movement is fast.

9. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
Look at the light coming from our Sun
- Use a spectroscope to view the light coming in through the window

10. Specification Aims By the end of this lesson you should be able to…
If you pass the light through a gas something different is seen…
Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
helium
Some wavelengths of light are absorbed by the gas – an “absorption spectrum”.

11. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
If the light source is moving away the absorption spectra look a little different…
Before
After
It is red - shifted

12. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
The Doppler Effect also occurs for a moving light source. If the source is moving away from us we will observe longer wavelengths
Before
After

13. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
Edwin Hubble observed the light from many distant galaxies and made a critical observation. He found;
Almost all galaxies were red-shifted
The most distant galaxies were the most red-shifted.

14. Almost all galaxies were red-shifted
Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
Edwin Hubble observed the light from many distant galaxies and made a critical observation. He found;
Almost all galaxies were red-shifted
The most distant galaxies were the most red-shifted.
This means the distant galaxies must be moving away from the Earth.
This means that very distant galaxies must be moving faster than near.

15. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
Photo credit: © 2006 Jupiterimages Corporation

16. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
Light from other galaxies has a longer ____________ than expected. This shows that these galaxies are moving _______ from us very quickly.
This effect is seen to a greater extent in galaxies that are _________ away from us. This indicates that the further away the galaxy is, the ________ it is moving. This shifting of light towards the red end of the spectrum is called the ‘____ _____’.
This evidence seems to suggest that everything in the universe is moving away from everything else, and that this process started around 14 _____ years ago. This is the ____ ________ Theory.

17. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
Hubble's Data

18. What would blue shifted light indicate?
Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
What would blue shifted light indicate?
Objects moving towards us will experience a shift towards the blue end of the spectrum.

19. Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
The Big Bang Theory
About 13.7 – 13.8 billion years ago, all the matter in the Universe was compressed into a very small space and it began to spread out.
The observations of red-shift fit this pattern very well because they confirm that the universe is expanding

20. Now complete the question sheets 
Specification Aims By the end of this lesson you should be able to…
Explain what is meant by the Doppler effect in sound waves and how the same theory can be used to explain changes in wavelength of light.
Describe how the light from distant stars may be red-shifted and explain the implication of this on our understanding of the universe.
Describe the observations of Edwin Hubble and how these contributed to our understanding of the universe.
Now complete the question sheets 