Notes:

The Beats Interactive is an adjustable-size file that displays nicely on smart phones, on tablets such as the iPad, on Chromebooks, and on laptops and desktops. The size of the Interactive can be scaled to fit the device that it is displayed on. The compatibility with smart phones, iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.

 

Teaching Ideas and Suggestions:

This Interactive is intended for use near the middle to later stages of a learning cycle on waves and sound. It provides a great illustration of how sound waves from two different sources interfere to form a resulting pattern. When the frequencies of those sound waves are very close in value, the sound that is heard is referred to as beats. Beats are characterized by the perception of a sound whose loudness fluctuates from a maximum to a minimum. The frequency of fluctuation between the maximum and minimum loudness is known as the beat frequency and is equal to the difference in frequencies of the two sources. Humans can easily hear beat frequencies of 1 Hz and 2 Hz. A beat frequency of 2 Hz means that the loudness of the sound fluctuates from loud to soft and back to loud two times in every second. Frequencies as high as 7 Hz can be heard by most people. Additional information on beats can be found at our Tutorial page.

This Interactive makes a great follow-up to a demonstration of beats using two Tuning forks. As depicted in the simulation, one would ideally have tuning forks mounted on sound boxes in order to amplify the sound sources. A rubber band can be wrapped around the tines of one of he tuning forks in order to increase its mass and thus llower its frequency. An exceptional illustration of the demonstration can be found at The Kids Should See This website. If at all possible, be sure to conduct the demonstration live for your students.

We believe that the most valuable role of this Interactive is to help students understand the model that explains the perception of beats. Beats are an interference phenomenon. The perception of sound of maximum loudness occurs during moments when sound waves from the two sources are undergoing constructive interference. The perception of minimum loudness is observed when the sound waves from the two sources are undergoing destructive interference. By setting the Zoom level in the simulation to 10X or 32X or 100X, the two component waves are clearly visble and their interference can be shown to students.
 
The Physics Classroom has not prepared any activities for use with this Interactive. We are confident that teachers who use our website will come up with plenty of great ideas for using the Beats Interactive and we invite you to share those ideas with us. Please share your ideas on our social media websites (#TPCphint):
 
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Related Resources

There are numerous resources at The Physics Classroom website that serve as very complementary supports for the Beats Interactive. These include:
  • Reading:
    Lesson 3 of the Sound Chapter of the Tutorial are perfect accompaniments to this Interactive. The following page will be particularly useful in helping students to understand beats as an example of sound wave interference:

    Interference and Beats

     
  • Minds On Physics Internet Modules:
    The Minds On Physics Internet Modules include a collection of interactive questioning modules that help learners assess their understanding of physics concepts and solidify those understandings by answering questions that require higher-order thinking. Assignment WM6 of the Wave Motion module provides a great complement to this Interactive. Minds On Physics is best used in the middle to later stages of the learning cycle. Visit the Minds On Physics Internet Modules.

     
  • Curriculum/Practice: Several Concept Development worksheets at the Curriculum Corner will be very useful in assisting students in cultivating their understanding, most notably ...

    Interference of Waves

    Visit the Curriculum Corner.

     
Additional resources and ideas for incorporating the Beats Interactive into an instructional unit on Waves and Sound can be found at the Teacher Toolkits section of The Physics Classroom website.  Visit Teacher Toolkits.
 
 
 
 

Credits

The Physics Classroom would like to extend a special thanks to Nerd Island Studios for the creation of this HTML5 Interactive. Visit http://www.nerdislandstudios.com to see more great stuff by Nerd Island Studios.
 



 
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