Demonstration : Doppler Shift
Topic/Concept: Doppler Shift
Type of Activity: Demonstration
Prerequisite knowledge required: Need to know what Doppler shift is
Resources required: Chris Anderson’s buzzer on string (or something similar)
Learning Objectives: Develop physical intuition about Doppler shift
Common misconceptions:
Detailed description of activity:
Note that we also have a very nice demo of the Doppler shift in sound waves – a little buzzer on a string. If you spin it around your head, the students can hear the change in pitch as it moves toward and away from them (though you can’t really hear it as you stand in the middle). You can vary the speed to show how that affects the pitch. It may be best to introduce this correlation early on in the discussion of light; the musicians in the class will get a kick out of thinking of low notes as “red” and high notes as “blue.” (And if talking about energy, you can point out that it takes more energy to sing a high note than a low one.)
Assessment:
Associated files and images: None.
Comments: The only difficult concept is the association of the pitch of a sound wave with the wavelength of a light wave.
By Jennifer Hoffman (10/99)
In my freshman physics class, my prof brought in this tank of water, and a little bent wire that rose and fell on the water surface rhythmically. Each time it did, it created a wave. You could then make the wire move across the water surface, and watch the waves get compressed in the direction of the wire’s travel, while the waves expanded away from one another in the opposite direction of the wire’s travel. That was a cool and helpful demo. I often wish i had that wire thingy. I bet someone handy could make one.
Laura Chomiuk | 17 April, 11:16 PM | #