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The World-Famous Constructive Interference 3 Act

by Patrick ehrenreich


Act One

  • Patrick ehrenreich

    Patrick ehrenreich

    May 18, 2015

    A friend and I each grab one end of a slinky and make an individual wave. What will the amplitude be when we make both waves simultaneously?

  • The video is made to mirror each of the three steps. Pause after each step in the video to allow time for calculations and guesswork.

Act Two

  • The tape on the floor serves as a scale for the amplitude of the wave. Each of the small pieces is 20 centimeters end-to-end, and the large piece is 50 centimeters end-to-end.

  • Constructive interference: noun. The interference of two or more waves of equal frequency and phase, resulting in their mutual reinforcement and producing a single amplitude equal to the sum of the amplitudes of the individual waves.

Act Three

  • Teacher note
    The amplitude of the combined waves when constructive interference occurs is 40 centimeters, since the amplitude of each individual wave is 20 centimeters and the waves are perfectly in phase with one another. Watch part 3 of the video for visual conformation of the phenomenon.


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