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What is the wavelength

  1. Apr 6, 2009 #1
    1. The problem statement, all variables and given/known data
    An FM station broadcasts at 107.5 MHz. What is the wavelength of this wave?


    2. Relevant equations
    well i know that speed = frequency X wavelenght but if i dont know the speed then how can i find the length


    3. The attempt at a solution
    so i found out that the average length of a radio wave is about 3 m and tried it but it was the wrong answer. i am just confused how to find the wavelength with only the frequency.
     
  2. jcsd
  3. Apr 6, 2009 #2
    oh so i think this is a second part to the question also. How long will it take for a message from Earth to reach the first astronauts who arrive on Mercury; assume Mercury is at its closest approach to Earth (9.17×107km)?

    well i just did that distance 9.17x10^7 km and got it to m and then divided is by 3x10^8 which is the speed of light so what did i do wrong for that part?
     
  4. Apr 6, 2009 #3

    Hootenanny

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    Nothing. You working is fine to either you have made a numerical error somewhere, or you have not entered the correct number of significant digits.
    If you were to assume that the radio wave was travelling through space (which is a pretty good approximation for air), what would be its speed?
     
  5. Apr 6, 2009 #4
    would i just use 3x10^8 m/s?
     
  6. Apr 6, 2009 #5
    oh wait i think i did have my decimals mixed up for the problem about the time. haha thanks
     
  7. Apr 6, 2009 #6

    Hootenanny

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    Sounds good to me.
    No problem.
     
  8. Apr 6, 2009 #7
    cool thanks it worked!
     
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