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Unformatted text preview: Physics 7C Fall 2011 Practice Final Exam 2 Cover Sheet INSTRUCTIONS: Right now , as soon as you get this part of the exam: 1. Fill in this cover sheet completely . 2. Put your name and your DL section on each page of the exam. This is important!! The pages are separated for grading! 3. Count the pages of the nal exam. There should be 10 pages total with problems and questions on pages 2 - 9. If you nd this is not the case, inform the proctor IMMEDIATELY. It is your responsibility to have a complete exam. Remember: * You may not know the answer or immediately know what to do when you rst read a question. You are being tested on your ability to think. So think about how you can apply the general models and methods you have learned to the particular situations discussed in the questions. * Dont Cheat! We automatically report anyone suspected of cheating to Student Judicial Affairs. I certify by my signature below that I have read the above instructions and that I will abide by the UC Davis Code of Academic Conduct. This includes not copying from anyone elses nal not letting any other student copy from my nal not discussing this nal exam with any student who has not yet taken it, nor providing any information, written or oral, that might get to a student who has not yet taken it Name (Print Clearly): Last rst 7B Lecture (A, B, C, or D) _______ DL Section Number: (This is a number between 1 and 11) Signature:______________________________________ You may begin the nal as soon as you have completed this and the following: put your name, DL section number, and rst three letters of your last name on each of the following eight pages (pp. 2-9) . 1. Two radio antennas are broadcasting a signal made up of three frequencies: 150 kHz, 300 kHz and 600 kHz. Both antennas are broadcasting ALL THREE frequencies. The signals are in phase and have the same amplitude as they leave their antenna. You are positioned so that you are 1000 m closer to antenna #1 than you are to antenna #2. Show all your reasoning and work. (The speed of electromagnetic waves is 3x 10 8 m/s). a. What are the wavelengths of the three signals? wavelength = (3x10 8 m/s)/f, so the wavelengths are 2000 m, 1000 m, and 500 m respectively. b. At the position described above, which of the signals do you pick up? Since you are 1000 m closer to one antenna, this is is a path length difference of one-half wavelength for the 150 kHz signal, one full wavelength for 300 kHz, and two full wavelengths for the 600 kHz signal. Thus there is destructive interference for the 150 kHz signal, and only the 300 kHz and 600 kHz signals are received....
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This note was uploaded on 02/21/2012 for the course PHY7C C taught by Professor Many during the Spring '12 term at UC Davis.
- Spring '12