1. Coffaro 4/20081 Key Terms Wave- traveling disturbance of energy Longitudinal Wave- compression wave; molecules in medium are pushed back and forth parallel to motion Transverse Wave- wave that moves up and down Amplitude- height of wave Wavelength- distance of one wave cycle Frequency- number of waves in a unit of time; measured in Hertz (Hz) Velocity- speed of a wave Medium- substance that allows energy to pass

2. Coffaro 4/20082 April 8, 2008 Warm Up: Write question and answer. Q: What are the two kinds of waves from the video yesterday? What do waves travel through?

3. Coffaro 4/20083 Transfer of Energy by Waves MTHS Physical Science

4. Coffaro 4/20084 What are waves? Mechanical waves are a disturbance in matter that carries energy from one place to another.

5. Coffaro 4/20085 What do waves require? A medium, or matter to travel through  What can act as mediums? Solids, liquids or gases

6. Coffaro 4/20086 How do we create a mechanical wave? When a source of energy causes a vibration to travel through a medium  Ex. When you shake a rope How? Wave that results is vibration that carries energy along the rope What is a Vibration?  back and forth motion

7. Coffaro 4/20087 What are the Types of Mechanical Waves? Transverse Waves Longitudinal Waves Surface Waves

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9. 9 What are Transverse Waves? A wave that moves up and down This type of wave causes the medium to vibrate at right angles to the direction in which the wave travels Highest point above rest position is called the crest Lowest point below rest position is the trough

10. Coffaro 4/200810 Wave diagram

11. Coffaro 4/200811 Examples of Transverse Waves Electromagnetic Waves

12. Coffaro 4/200812 What are Longitudinal Waves? also called a compression wave because particles in medium are spaced close together molecules in medium are pushed back and forth parallel to motion vibration of the medium is parallel to the direction the wave travels

13. Coffaro 4/200813 Examples of Longitudinal Waves Sounds Explosions Earthquakes

14. Coffaro 4/200814 What are surface waves? Waves that travel on surface separating two media Most Familiar surface waves are ocean waves

15. Coffaro 4/200815 What are the basic characteristics of waves?

16. Coffaro 4/200816 What is frequency of a wave? The number of wave cycles in a given unit of time Measured in cycles per second, or Hertz (Hz)

17. Coffaro 4/200817 What is the period of a wave? Time required for one cycle, a complete motion, to return to its starting point

18. Coffaro 4/200818 What is wavelength of a wave? Distance between a point on one wave and the same point on the next cycle of the wave Increasing frequency decreases wavelength

19. Coffaro 4/200819 How do you calculate speed of wave? speed = wavelength x frequency m/s m Hz Example: One end of the rope is vibrated to produce a wave with a wavelength of 0.25 meters. The frequency of the wave is 3.0 Hz. What is the speed of the wave?  Wavelength= 0.25 m  Frequency= 3.0 Hz  Speed= ? Speed = Wavelength x Frequency

20. Coffaro 4/200820 What is amplitude of wave? The height of the wave Maximum displacement of medium from rest position The more energy a wave has, the greater is its amplitude

21. Coffaro 4/200821 How do waves behave? Reflection Refraction Diffraction Interference

22. Coffaro 4/200822 What is reflection? Occurs when wave bounces off surface it can not pass through Does not change speed or frequency of wave, but tends to flip wave upside down

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24. Coffaro 4/200824 What is refraction? Bending of a wave as it enters a new medium at an angle As it enters a medium at angle, refraction occurs because one side of the wave moves more slowly than the other side Only occurs when two sides of wave travel at different speeds

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26. Coffaro 4/200826 What is diffraction? The bending of wave as it moves around an obstacle or passes through a narrow opening Wave diffracts more if its wavelength is large compared to size of opening or obstacle

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28. Coffaro 4/200828 What is interference? Occurs when two or more waves overlap and combine together Two types of interference:  Constructive  Destructive- occurs when two or more waves combine to produce a wave with smaller displacement

29. Coffaro 4/200829 Constructive- occurs when two or more waves combine to produce a wave with a larger displacement

30. Coffaro 4/200830 Destructive- occurs when two or more waves combine to produce a wave with smaller displacement