Interference Patterns & Wavelength
Obj: Study constructive and destructive interference to determine wavelength.
Materials: wave tank setup

Methods & Analysis
1.  Set up the ripple tank with 2 wave point sources approximately 4 cm apart.
2.  Carefully sketch the pattern on your data sheet, showing the constructive and destructive interference areas.  Draw a line down the center of each antinode; label as n =  0 (center),1,2,3, etc. as discussed in class.
3.  Label all nodes and antinodes.
4.  Mark a single point on an antinode; measure the distance (d) back to each point source.  The DIFFERENCE, d₂ - d₁, is a whole number integer of one λ.
5.  Find:  λ = d₂ - d₁ / n   where n = 1,2,3 from which you measured.
6.  Rotate the point sources out of the water.  Using only the long board as the wave generator, place two barriers in line with each other about 10 cm apart.  Roughly sketch the diffraction pattern showing how much diffraction is occurring.
7.  Repeat for the barriers #1 cm apart.  Draw a conclusion about the amount of barrier separation and the amount of diffraction.
8.  Explain what is causing the antinodes and nodes (be specific!).  Why does diffraction occur at a boundary.

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