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Destructive Interference

  • Thread starter rteng
  • Start date
  • #1
26
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Homework Statement



1670a.jpg

1670b.jpg

1670c.jpg


Homework Equations



destructive interference occurs at 0.5(lambda), (3/2)(lambda),...



The Attempt at a Solution



I found the path difference to be:
d=sqrt(4+x^2)-x

and this has to be equal to (n)(lambda)/2 where n is an odd integer for destructive interference

this does not work out algebraically for me...as the x^2-x^2=0

is this path difference not correct?

do I just use f(n)=(nv)/(2d) to find d?
 

Answers and Replies

  • #2
47
0
Why did you do: x^2-x^2=0? Where does that come from?
 
  • #3
26
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ok I found my path difference to be sqrt(4+x^2)-x

so if I equate this to (n)(lambda)/2

then: sqrt(4+x^2)-x=(n)(lambda)/2

4+x^2-x^2=(n^2)(lambda^2)/4

there is my problem...
 
  • #4
47
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Do you know how to find lambda?
 
  • #5
47
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Oh, (sqrt(4 + x^2) - x)^2 = (sqrt(4 + x^2) - x) * (sqrt(4 + x^2) - x)
You don't just square the terms.
 
  • #6
26
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ah yes...of course

I think that should be the proper way to solve this problem...at least for a and b

now on to c...
 
  • #7
26
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ok I do not understand c
can anybody help?
 
  • #8
26
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I would say that the only way for which there be no destructive interference is if x is 0
but that revelation is really vague for me...could it be correct?
 
  • #9
26
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the I get f=86Hz
 

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