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Homework Help: Second Nodal Lines

  1. Feb 7, 2005 #1
    Ok here's the problem:
    Waves are produced by two point sources S and S' vibrating in phase. SEe the accompanying diagram. X is apoint on the second nodal line. The path difference SX - S'X is 4.5cm The wavelength of the waves is approxiately______.

    ````` o X
    So------ o S'

    I know what the answer is, but I really don't understand where this second nodal line would occur. :confused:
    Last edited: Feb 7, 2005
  2. jcsd
  3. Feb 8, 2005 #2

    Doc Al

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    Staff: Mentor

    Nodal lines occur where the waves from the two sources destructively interfere. The first nodal line occurs where the path difference equals [itex]\lambda/2[/itex], the second occurs where the path difference equals [itex]3/2 \lambda[/itex], etc.

    So the second nodal line is the set of all points that are [itex]3/2 \lambda[/itex] closer to one source than the other. (Note that there are two nodal lines for each path difference: one on either side of the central antinodal line, which is a straight line bisecting the line between the sources.) This set of points forms a hyperbola.

    You might find this site helpful: http://www.glenbrook.k12.il.us/gbssci/phys/Class/light/u12l3b.html [Broken]
    Last edited by a moderator: May 1, 2017
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