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Homework Help: What is R

  1. Nov 5, 2007 #1
    Sound waves move from the left(R) to right(L) from a tube.
    In the tube, the sound waves are split into 2 w/ radius R (half circled shaped)
    a) if sound emitted has a freq of 444Hz, what is the min value of R that will lead to max L?
    b) what is the smallest R leads to min sound at L?

    1. The problem statement, all variables and given/known data
    freq. of 444Hz

    2. Relevant equations

    3. The attempt at a solution
    I tried using the first eqn to solve for L, then using the 2nd solving for lambda and thinking it would be one of the two. but im completely lost now.
    I dun get this question at all...

    Max sound is constructive.. soo.... :yuck:
    attached is the picture w/ the Question

    Attached Files:

    Last edited: Nov 5, 2007
  2. jcsd
  3. Nov 6, 2007 #2
    i really need hints please =s

    i have a midterm on this this week =s
  4. Nov 6, 2007 #3


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    Staff Emeritus
    Science Advisor

    Yes - this would be a problem of max (constructive) and min (destructive) interference.

    The length of the curve is [itex]\pi[/itex]R, and one has find the R such that the sounds add or cancel each other. The straight path has a length 2R.

    What is the condition for interference with respect to difference between the two lengths, i.e. when is interference constructive/destructive?

    lambda=V/freq is correct - so what is the wavelength of a 440 Hz wave?

    Here is a reference - http://hyperphysics.phy-astr.gsu.edu/hbase/sound/interf.html
    Last edited: Nov 6, 2007
  5. Nov 6, 2007 #4
    ah I see
    Thanks. i figured it out soon afterwards.

    i thought we didnt learn that section. so i tried to solve it bying the phase eqn for construction and destruction waves x_x

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