# Homework Help: Questions concerning Dopplers Effect and Wave Phenomena

1. Jun 24, 2012

### Daaniyaal

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. Jun 25, 2012

### Infinitum

Hi Daaniyaal! Welcome to Physics Forums

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:
http://en.wikipedia.org/wiki/Diffraction#Single-slit_diffraction
http://www.math.ubc.ca/~cass/courses/m309-03a/m309-projects/krzak/index.html