1. Waves Notes 1 Definition, behavior, and classification

2. What is a wave? A WAVE is a vibration or disturbance in space.

3. What is a wave? Waves transfer energy without transferring matter.

5. How are waves classified? Waves can be classified by WHAT they move through or by HOW particles are vibrated.

6. What material do waves move through? A MEDIUM is the substance that waves travel through and need to have in order to move.

7. Classification of Waves According to what they move through (Medium) Electromagnetic waves Mechanical Waves

8. Electromagnetic Waves waves that can travel through matter or empty space where matter is not present.

9. radio waves microwaves infrared waves visible light ultraviolet rays X-rays Gamma Rays Electromagnetic Waves

10. Mechanical Waves Needs a medium require the particles of the medium to vibrate in order for energy to be transferred.

11. water waves earthquake/seismic waves sound waves waves that travel down a rope or spring Mechanical Waves

12. Classification of Waves According to how particles are vibrated. Transverse waves Longitudinal Waves

13. Transverse Waves Displaces particles perpendicular to the motion of the wave

14. science.hq.nasa.gov/kids/imagers/ems/waves3.html

15. Longitudinal Waves Cause the particles of a medium to move parallel to the direction of the motion of the wave.

16. Longitudinal Waves Has a crowded area causing a high- pressure region called compression, and the opposite is rarefaction

17. http://www.lcse.umn.edu/specs/labs/glossary_items/rarefaction_spring.html

18. Transverse and Longitudinal Wave Which is which?

21. Wave Characteristics Wavelength (λ) The distance from crest to crest (or trough to trough); expressed in meters

22. Wave Characteristics Amplitude (A) The distance of crest (or trough) from the midpoint of the wave

25. Wave Characteristics Frequency (f) The number of waves that passed a fixed point per second; measured in hertz (Hz)

26. Periodic Wave Characteristics Period (T) The time it takes a wave to travel a distance equal to a wavelength; measured in seconds T= 1/f

27. Periodic Wave Characteristics Period (T) start end

28. Period (T) start end

29. Period (T) endstart

30. Periodic Wave Characteristics Wave velocity (v) Distance travelled by a wave crest in one period v= λ/T

31. Wave Behavior What happens when… A wave meets a hard surface like a wall? A wave enters a new medium? A wave moves around an obstacle? A wave meets another wave?

32. Reflection When a wave hits a surface through which it can’t pass through, it bounces back. All types of waves can be reflected.

33. Reflection When a wave hits a surface through which it cannot pass, it bounces back. All types of waves can be reflected.

34. Reflection Reflection does not change the speed or frequency of the wave, BUT the wave can be flipped upside down!

35. Refraction The bending of a wave as it enters a new medium. It is caused by a change in the speed of the wave as it moves from one medium to another – Greater change in speed = more bending of the wave

36. Refraction

37. Draw a diagram for both refraction and diffraction from the next slides.

38. Refraction

39. Diffraction The bending of a wave as it moves around an obstacle or passes through a narrow opening.

40. Diffraction The scattering of a wave as it hits the edges of a boundary or tiny opening. The wave will curve around the boundary or outward through the opening.

41. Refraction vs. Diffraction Both are bending of waves, but refraction occurs when waves move through something, while diffraction occurs when waves pass around something.

42. Interference When two or more waves are moving through a medium at the same time, they may overlap or combine together.

43. Interference

44. Constructive Interference When two waves combine to make a wave with larger displacement or amplitude. – “Helping each other”

45. Destructive Interference Two or more waves combine to produce a wave with a smaller displacement.

46. Inverse Square Law Any wave gets weaker as it gets farther away from the source. The intensity of the wave decreases by 1/d 2

47. Comparing Energy of Waves: Light Source of energy for Wave Mediums it can Travel Through Type of WaveSpeed of Wave How is the wave sensed? Electromagnetic Radiation Sun Vacuum Gases Liquids Transparent and translucent solids Electromagnetic Transverse 299,792,458 m/s In space Eyes Photon detector

48. Comparing Energy of Waves: Sound Source of energy for Wave Mediums it can Travel Through Type of WaveSpeed of Wave How is the wave sensed? Vibrations caused by impact Mechanical energy Gases Liquids solids Mechanical Longitudinal 340 m/s in air ears Oscilliscope

49. Comparing Energy of Waves:Earthquake Source of energy for Wave Mediums it can Travel Through Type of WaveSpeed of Wave How is the wave sensed? Mechanical energy suddenly released when rocks break solids Liquids (p waves only) Mechanical Longitudinal (p waves) Transverse (s waves) 6000 m/s (p wave) 4000 m/s (s wave) In granite Feel it shaking Seismograph

50. Comparing Energy of Waves: Heat Source of energy for Wave Mediums it can Travel Through Type of WaveSpeed of Wave How is the wave sensed? Electromagnetic radiation Thermal energy released Vacuum Gasses Liquids Solids Electromagnetic infrared wave Transverse 299,792,458 m/s in space Heat receptors in skin Infrared camera thermometer

51. Solve the problems on the following slides in your notebooks. Give them an honest try by looking at your notes from Wave Notes 1. The problems are probably more easy than you think.

52. Problem Solving Time! 1.A wave in a spring has a wavelength of 0.1 meters and a period of 0.2 seconds. What is the velocity of the wave? v= λ/T v = 0.1 m / 0.2 s v = 0.5 m/s

53. Problem Solving Time! 2.Find the wavelength of a wave in a rope that has a frequency of 2.0 Hz and velocity of 0.4 meters/second. (Hint: Start by solving for the period) T = 1/f; v= λ/T T = 1/2.0 Hz; T=0.5 O.4 = λ/0.5 λ = 0.2 m

54. 0 cm 5 -10 -5 10 3. What is the amplitude of the wave? Amplitude = 5cm

55. Problem Solving Time! 4.A hiker shouts on top of a mountain toward a vertical cliff, 688m away. The echo is heard 4s after. a. What is the velocity of sound? (Hint: velocity = distance / time) b. The wavelength of the sound is 0.75m. What is its frequency? (New equation: frequency = velocity / wavelength) c. What is the period of the wave?

56. Problem Solving Time! a)Speed v = d/t v = 688m/2s v = 344m/s 2 s 4 seconds

57. Problem Solving Time! b)Frequency v = λ/T; f = v/λ f = 344m/s / 0.75m f = 458.67 Hz 4 seconds

58. Problem Solving Time! c)Period T = 1/f T = 1/458.67 Hz T = 2.18x10 -3 s 4 seconds

59. Problem Solving Time! 5.If the frequency of a sound wave is doubled, what happens to the period of the same sound wave? The period will be halved.

60. Problem Solving Time! 6.If the velocity of wave is doubled, what happens to the frequency of the same wave if the wavelength is constant? (frequency = velocity / wavelength) The frequency will be doubled.

61. Problem Solving Time! 6.If the velocity of wave is doubled, what happens to the frequency of the same wave if the wavelength is constant? (frequency = velocity / wavelength) The frequency will be doubled.

62. Problem Solving Time! 7.(BONUS!) If the wavelength is halved and the frequency is quadrupled, what will be the speed of the wave? (in multiples of v) (velocity = wavelength * frequency) 2V.