1. PHYS/MUS 102, SPRING 2015 Wave Interference

2. Longitudinal drawn as Transverse Waves 1. It’s a longitudinal wave 2. But it can be represented by drawing our typical sine wave

3. What happens when 2 pulses interfere? Constructive Interference Destructive Interference

4. Wave interference (aka superposition)

5. What happens when 2 sources with different frequencies interfere?

6. Answer: Beats! f sum = Questions: Where does occur in a music context, and what will this sound like?

7. Tune up

8. Two-source interference

9. Quantifying intensity maxima m = 0 m = 1 m = 2 m = -1 m = -2 d L z Source 1 Source 2

10. Phase shift 

11. Predicted (theoretical) locations of maxima/minima Maxima occur where: m = d sin  = d (z/L) m = …-2, -1, 0, 1, 2 Minima occur where: (m+1/2) = d sin  = d (z/L)

12. Symphony of Superposition

13. Image sources Boston University http://sirius.ucsc.edu/demoweb/cgi-bin/?waves-visible-intermodel http://www.paulfriedlander.com/text/timetravel/experiment.htm http://web.sbu.edu/chemistry/wier/electrons/young.html http://hyperphysics.phy-astr.gsu.edu/hbase/sound/beat.html#c2 http://www.animations.physics.unsw.edu.au/waves-sound/interference/ http://www.animations.physics.unsw.edu.au/jw/beats.htm http://www.phys.unsw.edu.au/jw/uncertainty.html