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WAVES

WAVES. Chapter 25. The Nature of Waves. Ia. Wave : a repeating disturbance or movement that transfers energy through space or matter . Ex light, sound, radio. Ib. Medium:. any material that a wave transfers energy through ex. Water is the medium for ocean waves.

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WAVES

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  1. WAVES Chapter 25

  2. The Nature of Waves Ia. Wave: a repeating disturbance or movement that transfers energy through space or matter. Ex light, sound, radio

  3. Ib. Medium: any material that a wave transfers energy through ex. Water is the medium for ocean waves

  4. II. 2 Types of Waves 1. Transverse 2. Longitudinal (Compressional)

  5. Motion of Molecules 1a. Transverse Waves Direction of Wave Particles of the medium vibrate perpendicular (up & down) to the direction the wave is moving.

  6. 2a. Longitudinal Waves particles vibration is parallel to the direction of the wave. These waves require a medium (such as air or water) through which to travel. ex. Sound waves (looks like a spring) Direction of Movement Direction of Wave

  7. III. Wave Properties- Definitions • Wavelength – the distance between one point on a wave and the nearest point just like it. The greek symbol is , called lambda. • Frequency – number of wavelengths () that pass a given point each second • Crest – the highest point of a transverse wave

  8. Definitions continued…. • Trough– the lowest point on a transverse wave • Amplitude – the measure of the energy of the wave (height for TW) ex. Large amplitude = more energy • Nodal Line – an imaginary line, it is the usual resting position of a wave

  9. IV. Transverse Wave Diagrams Draw a transverse wave large enough to label 6 parts .

  10. Parts of a Tranverse Wave Crest Crest is the top of the wave

  11. Trough Trough is the bottom of the wave

  12. Wavelength Wavelength Wavelength The wavelength is the distance from one crest of a wave to the corresponding crest in the next wave or from one trough to the next trough.

  13. Amplitude Amplitude is the distance from the nodal line to the crest or the nodal line to the trough.

  14. V. Parts of a longitudinal wave are: A. A compression is the part where the particles of matter are pushed close together. B. A rarefaction is the part where particles of matter are spread apart. C. The wavelength is one complete compression and one complete rarefaction. SI unit is in meters.

  15. Parts of a Longitudinal Wave Compression the part where the particles of matter are pushed together

  16. Longitudinal Wave Diagrams Rarefaction part where particles of matter are spread apart

  17. Parts of a Longitudinal Wave Wavelength Compression & Rarefaction together

  18. Compressional Wave compression rarefaction

  19. VI. Calculating Wave Speed Frequency is the number of waves that pass a given point each second. The SI unit for frequency is Hertz(Hz).

  20. At a constant speed, there is an inverse relationship between frequency and wavelength:

  21. V = F  V = Velocity of the wave (m/s) F = Frequency (hertz) (hz) = wavelength (m) is the Greek symbol called “lambda”.

  22. Measuring Transverse Waves Interactive Website

  23. V = F   Practice Problems A. What is the velocity of a wave that has a frequency of 20hz and a wavelength of 3 m ? GIVENFORMULA SUB ANSWER & UNIT V = F  

  24. V = F   Practice Problems A. What is the velocity of a wave that has a frequency of 20hz and a wavelength of 3 m ? GIVENFORMULA SUB ANSWER & UNIT V=V F = 20hz  = 3m V = F  

  25. V = F   Practice Problems A. What is the velocity of a wave that has a frequency of 20hz and a wavelength of 3 m ? GIVENFORMULA SUB ANSWER & UNIT V = 20  3 V=V F = 20hz  = 3m V = F  

  26. V = F   Practice Problems A. What is the velocity of a wave that has a frequency of 20hz and a wavelength of 3 m ? GIVENFORMULA SUB ANSWER & UNIT V=V F = 20hz  = 3m V = F   V = 20  3 60 m/s

  27. V = F   Practice Problems B. What is the frequency of a wave traveling at 16 m/s with a wavelength of 8 m ? GIVENFORMULA SUB ANSWER & UNIT V = F  

  28. V = F   Practice Problems B. What is the frequency of a wave traveling at 16 m/s with a wavelength of 8 m ? GIVENFORMULA SUB ANSWER & UNIT V=16m/s F = F  = 8m V = F  

  29. V = F   Practice Problems B. What is the frequency of a wave traveling at 16 m/s with a wavelength of 8 m ? GIVENFORMULA SUB ANSWER & UNIT V=16m/s F = F  = 8m V = F   16 = F  8

  30. V = F   Practice Problems B. What is the frequency of a wave traveling at 16 m/s with a wavelength of 8 m ? GIVENFORMULA SUB ANSWER & UNIT V=16m/s F = F  = 8m 16= F  8 8 8 V = F  

  31. V = F   Practice Problems B. What is the frequency of a wave traveling at 16 m/s with a wavelength of 8 m ? GIVENFORMULA SUB ANSWER & UNIT V=16m/s F = F  = 8m V = F   16= F  8 8 8 2 hz

  32. C. What is the wavelength of a wave traveling at 9 m/s with a frequency of 36 hz ? GIVENFORMULA SUB ANSWER & UNIT

  33. V = F   Practice Problems C. What is the wavelength of a wave traveling at 9 m/s with a frequency of 36 hz ? GIVENFORMULA SUB ANSWER & UNIT V=9m/s F = 36hz  =  V = F  

  34. V = F   Practice Problems C. What is the wavelength of a wave traveling at 9 m/s with a frequency of 36 hz ? GIVENFORMULA SUB ANSWER & UNIT V=9m/s F = 36hz  =  V = F   9 = 36  

  35. V = F   Practice Problems C. What is the wavelength of a wave traveling at 9 m/s with a frequency of 36 Hz ? GIVENFORMULA SUB ANSWER & UNIT V=9m/s F = 36hz  =  V = F   9 = 36   36 36

  36. V = F   Practice Problems C. What is the wavelength of a wave traveling at 9 m/s with a frequency of 36 Hz ? GIVENFORMULA SUB ANSWER & UNIT V=9m/s F = 36hz  =  9 = 36   36 36 V = F   1/4 or 0.25 m

  37. VI. Reflection is the bouncing back of a wave ex. Your reflection in a mirror

  38. VII. The Law of Reflection: all waves bounce off of a surface at the same angle they strike the surface. Thee angle of incidence is equal to the angle of reflection. Normal

  39. VIII Refraction: the bending of a wave caused by a change in speedof the waveas it passes from one medium to another. Ex. Objects look distorted under water

  40. IX. DIFFRACTION: The bending of a wave as it passes an edge or opening Ex. Ocean waves change direction and bend after striking an island

  41. Diffraction of a Monochromatic Light Source Ripple Tank

  42. XI. Interference The combination of 2 or more waves – 2 types: a. Constructive Interference b. Destructive Interference

  43. a. Constructive interference occurs when waves align in sync – are added together Ex. in sound waves constructive interference causes a louder sound

  44. b. Destructive interference occurs when sound waves are out of sync. They subtract from each other. Ex. in sound waves destructive interference causes a softer sound

  45. XII. Resonance is the ability of an object to vibrate by absorbing energy at its natural frequency Ex. A “singing” wine glass

  46. http://www.howstuffworks.com/question603.htm singing wine glass” video Tacoma Bridge Disaster

  47. Tacoma Washington Bridge

  48. Tacoma Bridge -- Twist One sidewalk was 28 feet higher than the other. Tacoma Bridge -- Twist One sidewalk was 28 feet higher than the other.

  49. Tacoma Bridge -- Twist

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