1. Physics 11 Chapter #8 Vibrations and Waves Mr. Jean May 28 th, 2012

2. The plan: n Video Clip of the day n Science Fair Presentations n Introduction to waves n Ways to transmit & transfer energy n Wave interference

3. Science Fair: n Cher n Abby’s Group

4. In symbolic form or

5. Example Question: n A mass suspended from the end of a spring vibrates up and down 24 times in 36 seconds. What is the frequency and period of the vibration?

6. Example Question: n A mass suspended from the end of a spring vibrates up and down 24 times in 36 seconds. What is the frequency and period of the vibration?

7. Wave Characteristics: n http://www.brightstorm.com/scienc e/physics/vibration-and- waves/wave-characteristics/ http://www.brightstorm.com/scienc e/physics/vibration-and- waves/wave-characteristics/ http://www.brightstorm.com/scienc e/physics/vibration-and- waves/wave-characteristics/

8. 3.WAVE MOTION n n Energy is transported by particles or waves. n n A wave is a disturbance transmitted through a medium. n n Exception: light does not require a medium.

9. 4.WAVE SPEED The average speed is defined as

10. For a wave, if the distance traveled is a wavelength ( ), then the time to travel this distance is the period (T). Then or

11. is true for all waves. Note: v is dictated by the medium. (must change medium to change v) f is dictated by the source. (must change the source to change f ) Demo - Complete Bell Wave Machine

12. 5.TRANSVERSE WAVES Demonstration: Transverse Waves Examples: string musical instruments ripples on water electromagnetic waves

13. 6.LONGITUDINAL WAVES Video - Slinky Longitudinal Waves Parameters Rarefactions are regions of low density. Compressions (condensations) are regions of high density.  is the distance between successive rarefactions or successive compressions.

14. 7.INTERFERENCE Video - Superposition of Waves SlideSlide - Interference Slide

18. Constructive interference occurs when waves are in phase, that is when crests are superimposed and troughs are superimposed.

19. Destructive interference occurs when waves are out of phase, that is when crests are superimposed with troughs.

21. Interference is a characteristic of all waves. Demonstrations with Audacity

22. Standing Waves n n When two sets of waves of equal amplitude and wavelength pass through each other in opposite directions, it is possible to create an interference pattern that looks like a wave that is “standing still.” It is a changing interference pattern. n Demo - Rope and strobe n Demo - Mechanical overhead model

23. n There is no vibration at a node. n n There is maximum vibration at an antinode.  is twice the distance between successive nodes or successive antinodes.