1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Wavelength-easy problem

  1. Apr 10, 2007 #1
    Consider a commercial FM radio station that broadcasts at a frequency of 90.1 MHz. The associated electromagnetic radiation has a wavelength of ? m.

    I'm pretty sure that this is a very easy problem, but for some reason, I don'ts really get it.

    I was positive that I was supposed to use the equation c=wavelength*f

    and I converted the frequency into Hz by multiplying by 1E6

    and then I took the value of light (3E8) and divided it by my answer... is there something special about electromagnetic radiation the I failed to factor in?
  2. jcsd
  3. Apr 10, 2007 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Nope, assuming you did the arithmetic correctly, your answer should be correct (around 0.3 meters).
  4. Apr 10, 2007 #3
    thank you so much !
  5. Apr 13, 2007 #4
    According to de broglie relation lambda=h/mv ...which implies that velocity is inversely proportional to wavelength. But According to the reletion

    V=n lambda ... velocity is directly proportional to wavelength...... How That diffenence is Causesd ? Am i going wrong Somowhere ?
  6. Apr 13, 2007 #5


    User Avatar
    Science Advisor
    Homework Helper

    de broglie implies that velocity is proportional to lambda only for massive particles. Massless particles always travel at c. Where did you get V=n lambda? What is n?
  7. Apr 14, 2007 #6

    n is the frequency of the wave and V=n lambda is the basic Wave equation
  8. Apr 14, 2007 #7


    User Avatar
    Science Advisor
    Homework Helper

    Ok, so de broglie says lambda of a massive particle is inversely proportional to the velocity at a fixed mass. V=n*lambda says the the lambda of any wave is directly proportional to velocity at fixed frequency. The two statesments refer to different classes of objects with different properties held fixed. They are two quite different statements.
  9. Apr 16, 2007 #8
    okay. How it can be different ?de Broglie Equation deals with both particle and wave character ...and V=n*lambda equation deals with wave character.. Then how it can be different ?
  10. Apr 16, 2007 #9


    User Avatar
    Science Advisor

    The wave character of a massive particle. The formula cited in this problem is for electromagnetic radiation- light.
  11. Apr 16, 2007 #10


    User Avatar
    Science Advisor
    Homework Helper

    It's also important that different quantities are being held fixed in the two problems.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Wavelength-easy problem
  1. Wavelength problem (Replies: 1)

  2. Wavelength problem (Replies: 1)

  3. Wavelength problem (Replies: 7)

  4. Wavelength problem (Replies: 3)