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Homework Help: What happens to wavelength as temperature of air increases?

  1. Dec 24, 2016 #1
    1. The problem statement, all variables and given/known data

    what happens to wavelength if temperature increases?

    2. Relevant equations
    V= lambda * frequency

    3. The attempt at a solution
    I'm guessing since no change to frequency is stated?.. and I know that the speed of sound increases as temperature increase. The wavelength would have to increase in order to balance the equation V= lambda * frequency?
    But I'm not sure if it's correct or why and if frequency would be affected by temperature or not..
    I can't find a straight answer or explanation on google so here I am.
  2. jcsd
  3. Dec 24, 2016 #2
    The molecules vibrate faster at higher temperature.
    Temperature is defined as a measure of the average random motion of particles within a system.
    Last edited: Dec 24, 2016
  4. Dec 24, 2016 #3


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    Does the source of the sound (eg a signal generator driving a loudspeaker) change frequency when the temperature changes?
  5. Dec 24, 2016 #4


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    Staff: Mentor

    Hi turtlepower, Welcome to Physics Forums.

    Please try to make your Problem Statement self complete; helpers should be able to understand the complete problem by reading the problem statement alone. For example, it should state clearly that the problem pertains to sound in air.

    Those are good ideas. You should be able to find a source to confirm that the speed of sound in air (or any gas) varies with temperature. A web search should turn up a relevant equation (for example, the Hyperphysics web page on Sound Speed in Gases). You should also be able to make an argument about the frequency being constant -- think of how a given sound is projected into the air to begin with. Must the mechanism that produces the sound waves be tied to the temperature?

    Edit: Ah. I see that CWatters got there ahead of me!
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