Question

1. What is the objective of this assignment?
2. Briefly explain the Doppler Effect.
3. Set both the listener velocity v_L and the source velocity v_S to -2 m/s. Run the demo. What is the value of the frequency f_L? Does it change or remain constant?
4. Set the listener velocity v_L to -2 m/s and the source velocity v_Sto -5 m/s. Run the demo. What is the value of the frequency f_L? Does it change or remain constant? If there is a change, when does it take place? Explain.
5. Set v_L = 0. Set v_S = -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, and 5 m/s
   
   For each of the above values of v_S, record the value of f_L. That should give you 11 data points, each point corresponding to one value of v_S and its corresponding value of f_L. Type the values of v_S in column A and the values of f_L in column B.
6. On an x-y graph, plot the values of f_L as a function of the values of v_S(f_Lvalues go on the vertical axis and v_S values go on the horizontal axis). Include this plot in your report.
7. Describe the curve of f_L versus v_S, and write a short conclusion.

Answer 1

2) The Doppler effect is observed whenever the source of waves is moving with respect to an observer. The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding. It is important to note that the effect does not result because of an actual change in the frequency of the source. Using the example above, the bug is still producing disturbances at a rate of 2 disturbances per second; it just appears to the observer whom the bug is approaching that the disturbances are being produced at a frequency greater than 2 disturbances/second. The effect is only observed because the distance between observer B and the bug is decreasing and the distance between observer A and the bug is increasing.

The Doppler effect can be observed for any type of wave - water wave, sound wave, light wave, etc. We are most familiar with the Doppler effect because of our experiences with sound waves. Perhaps you recall an instance in which a police car or emergency vehicle was traveling towards you on the highway. As the car approached with its siren blasting, the pitch of the siren sound (a measure of the siren's frequency) was high; and then suddenly after the car passed by, the pitch of the siren sound was low. That was the Doppler effect - an apparent shift in frequency for a sound wave produced by a moving source.