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Rogue Physicist.  Free resources for physics education © 2006-2016 Dorian Pascoe.  Email: dorian@top-school.co.uk

Most resources are available under a Creative Commons Licence.  Visit our mirror at www.physicsweb.altervista.org

 

 

 

...the doppler effect...

 

 

 

Objectives:

 

  
 

 

Waves!

  

 

• Know that sound can undergo a change of pitch when the source or observer is moving.

 

 

 

• Be able to describe and explain phenomena involving changes of pitch due to a Doppler shift.

 

 

  

 

 

 

 

 

 

 

Task 1 - Starter

 

  
 

 

I know the answer!

 

 

  

 

Find someone who knows:

 

 

1) The definition of a transverse wave.

2) The definition of a longitudinal wave.

3) What is meant by refraction.

4) What is meant by diffraction.

5) Which kind of wave a sound wave is.

6) The range of human hearing.

 

 

Your teacher will tell you which questions to discuss.

  

 

 

 

 

 

 

 

Task 2 - The Doppler effect

 

  
 

 

Lots of waves!

 

 

 

  

 

Imagine a car moving at a constant speed of 70mph along the motorway - not speeding up or slowing down or changing gear.

 

• How would the engine sound from inside the car?

 

• How would this be different for an observer listening from the side of the road as the car drives by?

 

Your teacher will ask some of you to share your ideas about what would happen and why.  Now watch this video, and see if you were correct.

Video credit: Youtube

 

 

 

  

 

 

 

 

 

 

 

 

Task 3 - Doppler effect simulation

 

  
 

 

 

You will need the Yenka plug-in to run this software.

Download it here.

 

 

  

 

This simulation will help you understand why the wavelength and frequency of the sound changes as a fire engine moves past an observer.

 

 

Click the image above to load the simulation.

Simulation credit: Yenka.

 

 

 

Note: all Yenka software is free for home use; download the plug-in from the Yenka web site.  Schools and educational establishments will require a licence.

 

  

 

 

 

 

 

 

Task 4 - Explaining the Doppler effect

 

  
 

 

 

You will need the Yenka plug-in to run this software.

Download it here.

 

 

  

 

Write an explanation of the doppler effect, using as many keywords as you can from the list below:

 

 

wavelength          frequency          higher          lower          source          observer          towards          away          pitch          hear          longer          shorter          faster          slower          squashed          stretched

 

 

This task is available as a word document.

Click the image below to download it.

 

 

 

 

 

Your teacher will give you a copy of this diagram, to stick in your exercise book with your explanation.

 

 

Click the image above to download a printable copy of this diagram.

 

  

 

 

 

 

 

 

 

 

Homework

 

  
 

 

Let's catch some waves!

 

  

 

No homework task for this lesson.

 

 

Homework task coming soon!