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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

 

 

 

...hearing...

 

 

 

 

Objectives:

 

  
 

 

Waves!

  

 

• Know that sound waves are caused by vibrations.

 

 

• Know that sound waves can be shown on an oscilloscope.

 

 

• Be able to describe how the amplitude and wavelength of the oscilloscope trace relate to the loudness and pitch.

 

 

  

 

 

 

 

 

 

 

Task 1 - Starter

 

  
 

 

I know the answer!

 

 

  

 

Find someone who knows:

 

 

1) The law of reflection.

 

2) What does frequency mean?

 

3) What are the units of frequency?

 

4) The regions of the electromagnetic spectrum, in order.

 

5) Which type of EM wave has the highest energy?

 

6) Which type of EM wave has the lowest frequency?

 

7) Which type of EM wave has the longest wavelength?

 

 

 

 

Your teacher will tell you which questions to discuss.

 

  

 

 

 

 

 

 

Task 2a - Demonstrating sound waves

 

  
 

 

Lots of waves!

 

 

 

  

 

Your teacher will demonstrate a range of objects and devices which produce sound waves, including a loudspeaker connected to a signal generator.

 

 

 

Your teacher may:

 

1) Demonstrate range of frequencies you can hear.

 

2) Use a strobe light to show you the speaker cone moving.

 

3) Show you how the movement of the speaker affects a non-newtonian fluid.

 

 

 

 

 

 

What kind of wave is sound?  Think about the direction of oscillation - is it the same as the direction of wave motion?

 

 

 

  

 

 

 

 

 

 

 

Task 2b - Simulation & video

 

  
 

 

Wave vibrations.

 

 

 

  

 

Look at the simulation of a sound wave, below.  You should see wave fronts travelling forwards, but how are the individual particles moving?

 

 

 

Select wave type "sound" (2nd tab), expand the particle area with the green "+" sign, and select "particle view" with the radio buttons.  Use a low to medium frequency, and a large amplitude.

 

 

This video shows what happens when a tuning fork is used to disturb the surface of a beaker of water. 

 

Your teacher may demonstrate this to you as well!

Video credit: the Slow-Mo guys / Youtube.

 

  

 

 

 

 

 

 

 

 

Task 3 - Fill in the missing words

 

  
 

 

 

Sound waves!

 

  

 

Complete the text below, by filling in the missing words.

 

 

Click the image above to download this task as a word document.

 

 

 

Select words from the list below:

 

hertz         pitch         amplitude

oscilloscope         vibrations         second         vibrates

 

  

 

 

 

 

 

 

 

Task 4 - Sound waves on an oscilloscope

 

  
 

 

 

 

  

 

Sound waves can be displayed on the oscilloscope.  The amplitude and frequency of the oscilloscope trace is linked to the volume and pitch of the sound.

 

Your teacher will show you the oscilloscope traces for different sounds.

 

 

 

 

Look at the oscilloscope traces below:

 

 

 

1) Which wave has the highest pitch?

2) Which wave is the loudest?

3) Which wave has the highest frequency?

4) Which wave has the lowest frequency?

5) Which waves have the same volume?

 

 

 

 

Click the image below to download this task as a word document.

 

  

 

 

 

 

 

 

 

 

 

Homework

 

  
 

 

Let's catch some waves!

 

  

 

No homework task for this lesson.

 

 

Homework task coming soon!