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Doppler Effect Demos

Discussion in 'Science' started by Newstein, Feb 27, 2016.

  1. Newstein

    Newstein New commenter

    I have seen youtube videos on swirling a loudspeaker or mobile phone. Have you done anything different? How effective is it?
  2. MrVishniya

    MrVishniya New commenter

    A buzzer in a bag works very well in a classroom, you can throw it across the front of the class and it is obvious that the pitch is changing, attach a string and swirling around the head works well too. Talking about the weird noise a hairdryer makes as you move it back and forth will familiarize students too.
  3. phlogiston

    phlogiston Star commenter

    Search for Doppler effect on you tube and you will find several good videos of fire engines and the like. Kids all know this once they've thought about it - it's the explanations using waves they find harder to grasp!
    There's a nice Big Bang Theory clip that gets a smile.
  4. Newstein

    Newstein New commenter

    Have YOU DONE any demos yourself?
  5. phlogiston

    phlogiston Star commenter

    No. I can't think of a way of safely twirling anything that will produce a loud enough noise fast enough to show the effect.
    That's why I use youtube
  6. steve_cooke

    steve_cooke New commenter

    In the dark recesses of our cupboards I once found a large metal cylindrical whistle on a rubber tube. The kids found it hilarious as they watched me trying to coordinate blowing while,swinging the tube and whistle around my head, I invariably got clonked on the head! These days I stick to a buzzer on a string - it's sold as a "Doppler Ball" - but it is a buzzer on a string. There's still a risk of getting clonked, so the kids enjoy it, but with vertical circles rather than horizontal ones above my head the risk is small.
    With either whistle or buzzer the change in tone is very obvious and the kids all agree that they "get it", they can often get from there to the change in tone as sirens go by without prompting.

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