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Homework Help: Questions concerning Dopplers Effect and Wave Phenomena

  1. Jun 24, 2012 #1
    1. The problem statement, all variables and given/known data
    13. A man standing by the shore observes sea waves approaching at a frequency of 0.20Hz. A man on a boat observes that waves are approaching the boat at a frequency of 0.50Hz. The speed of the waves is 2.0ms–1. Which of the following gives a possible value for the speed of the boat and its direction?

    A) 3.0 ms^-1 away from the shore
    B) 3.0 ms^-1 towards the shore
    C) 1.2 ms^-1 away from the shore
    D) 1.2 ms^-1 towards the shore

    2. Relevant equations
    f′= f[v/(v±u)]
    f′= f[(v±u)/v]

    3. The attempt at a solution

    I tried to use the moving observer formula and moving source formula but neither worked :(

    Wave Phenomena:

    A parallel beam of light with a wavelength 600 nm passes through a single narrow slit and forms a diffraction pattern on a screen. The angle at which the first diffraction minimum is formed is 2.0 × 10–3 rad.
    What would be the angle of the first diffraction minimum for light of wavelength 400 nm?

    A. 3.0 × 10–3 rad
    B. 2.0 × 10–3 rad
    C. 1.3 × 10–3 rad
    D. 1.2 × 10–3 rad

    I don't know which formulas pertain to these, I would love some resources on this subject too, thank you!
  2. jcsd
  3. Jun 25, 2012 #2
    Hi Daaniyaal! Welcome to Physics Forums :smile:

    How did you use the formula?

    A hint : You can decide the direction by a little of intuition. The frequency as observed by the observer on the boat is more than the stationary observer. When does this happen?

    For example, if a siren is buzzing past, when would you hear a higher frequency? While approaching or when it is going away?

    Here you go:
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