Science Buddies: "Ask an Expert"

Hello! I want to conduct an experiment on Doppler effect in circular motion (with sound source moving in a circle and a stationary microphone recording) and to explore the dependency of initial frequency over the observed one, however, I'm afraid it won't be difficult enough. How do you think I can improve the experiment and question to make it more complex? Thank you!

phys_stud - I think this experiment can/will be extremely difficult! Physical placement of your microphone, size of your rotating platform and rotational speed of the sound source will provide some very interesting variables for an experiment. Not sure of what you want to make as an assumption or hypothesis relative to Doppler observation, but it is a very interesting setup. I think your measured output will resemble a cross between an amplitude modulated signal and a frequency modulated signal following a sinusoidal pattern. Good luck if you continue to the next step.

Rick Marz

I think you should first do some simple estimations using the Doppler equation to see how fast the movement needs to be in order to see a noticeable effect with your recording device. Best is if you have an audio source that can be set to a fixed frequency. Once you calculated the expected frequency shift, you can set to that to see if your recording device is able to discriminate the difference.

Once you settle on a speed, you will need to evaluate if this is feasible/safe with your setup.