path diff

1. PATH DIFFERENCE IN
WAVE INTERFERENCE

3. It may be easier to visualize it this way…
• Your feet are the sources of the
wave
• When a crest and a trough meet
the water is level

4. • This animation below gives the Idea behind
path difference
• The waves from the two different sources
have a different distance they must travel to
get to point A.

5. Question
A duet is performing at a talent show. They will be evenly spread out
on the stage 18 meters apart. The judge originally is 6 meters away
from them out in the audience right in between the performers.
During their performance he has to take a phone call and walks
towards the door as he realizes that his battery died. He is now 3
meters away from his judging desk but still 6 meters away from the
performers; it is found to be a point of minimum amplitude. What is
the wavelength of the waves coming from the singers (assume their
talent is to hold the same frequency and amplitude for a very long
time).

6. Solution
• Use Pythagorean theorem to find the lengths of C^2
• 13.42-8.49=4.96
• Wavelength = 4.96/2 = 2.48

7. images
• http://method-behind-the-music.com/mechanics/physics/
• http://www.daviddarling.info/encyclopedia/I/interference.html
• http://www.featurepics.com/online/Female-Feet-Pool-Water-
1219054.aspx
• http://www.antonine-
education.co.uk/Pages/Physics_2/Waves/WAV_07/Waves_7.htm