2. General Wave Behavior Physics of Music, Spring 2014

3. Key Terms traveling wave transverse wave longitudinal wave plane waves circular waves Huygen's principle reflection diffraction velocity frequency wavelength

4. What is a traveling wave? A disturbance which travels through a medium, transmitting energy from the source to the observer without any net transfer of mass. Animation courtesy of Dr. Dan Russell, Kettering University

5. Transverse Wave Transverse: displacement is perpendicular to direction of wave propagation Spring image source: http://www.factmonster.com/dk/science/encyclopedia/energy-waves.html Animation courtesy of Dr. Dan Russell, Kettering University

6. Longitudinal Wave Longitudinal: displacement is parallel to direction of wave propagation. Animation courtesy of Dr. Dan Russell, Kettering University Long. Spring image source: http://www.factmonster.com/dk/science/encyclopedia/energy-waves.html

7. Plane waves and Circular Waves Plane  circular (diffraction!) Image sources: (top) Berg and Stork, Physics of Sound, 3 rd ed. (bottom) UC Irvine Optics research group. CircularPlane

8. Huygen’s Principle A wavefront can be thought of as being composed by a large number of “wavelets”, each of which spread out spherically in time and space. Image source: Berg and Stork, Physics of Sound, 3 rd ed.

9. Law of reflection Angle of incidence equals angle of reflection.  i =  r Both angles are measured with respect to the normal (dashed line perpendicular to the surface) Image sources: http://www.dl.ket.org/physics/companion/thepc/compan/Light/Light-t.htm http://www.worsleyschool.net/science/files/reflectionlaw/page.html

10. Plane Wave Reflection and Ray Diagrams normal Ray diagram Image source: http://hyperphysics.phy-astr.gsu.edu/hbase/sound/reflec2.html#c1

11. Reflection from concave surface Image source: http://hyperphysics.phy-astr.gsu.edu/hbase/sound/reflec2.html#c1 (left); Berg and Stork, Physics of Sound, 3 rd ed. (right)http://hyperphysics.phy-astr.gsu.edu/hbase/sound/reflec2.html#c1

12. Applications of Reflection? Image source: D. Hall, Musical Acoustics (left)

13. Diffraction Tendency for waves to spread out as a result of passing by an edge (barrier or passing through a slit) Image source: http://innovativescience.blogspot.com/2011/02/diffraction.html Narrow aperture Wide aperture

14. Diffraction Patterns Diffraction in ripple tank Diffraction on a MUCH larger scale. Image sources: (top) http://scripts.mit.edu/~tsg/www/demo.php?letnum= Q%201&show=1 http://scripts.mit.edu/~tsg/www/demo.php?letnum= Q%201&show=1 Bottom: http://www.suntrek.org/factary/d.shtml

15. Diffraction in Action

16. Key Terms Wave Mechanics: Part II traveling wave transverse wave longitudinal wave plane waves circular waves Huygen's principle reflection diffraction velocity frequency wavelength

17. A Day at the Beach Check out the plane waves!!!

18. Travelling Waves Velocity (v): change in position per change in time v=  x/  t  vT Or… v = f x Animation courtesy of Dr. Dan Russell, Kettering University Wavelength ( ): spatial distance from crest-to- crest Frequency (f): how many times per second one particular point oscillates

19. t = t o t = t o + T

20. Travelling waves in ripple tank: high speed video (240 fps) Image from Arbor Scientific Ripple tank image, oblique view

21. Speed of Sound in Various Bulk Media Material Speed of Sound [m/s] Air (20 C)343 Brass3475 Sea Water1533 Wood~ 3600 Data from: http://www.engineeringtoolbox.com/sound-speed-solids-d_713.html