Aim: What are waves?

1. Aim: What are waves? Do Now: Make a list of at least 5 different types of waves. Homework: Study for quiz.

2. What is a wave? A disturbance that travels through matter or empty space, & transfers energy Ex. a ripple in a pond, or light from the sun

3. What is a medium? The matter through which a wave moves Ex. Solid, liquid, or gas a) Water is a medium for ocean waves b) Air is a medium for sound waves

4. What type of waves require a medium? 4. What types of waves don’t require a medium? Mechanical Waves Electromagnetic Waves Can travel through a vacuum (empty space) or a medium Ex) Light or X-Rays

5. What are 2 types of waves? 1. Transverse & 2. Longitudinal (a.k.a. Compressional)

6. How does a transverse wave move? The motion of the medium is at right angles to the direction of the wave Ex. A ripple in water, light, electromagnetic waves Medium  Transverse Wave Picture : Energy of the Wave

7. How does a longitudinal wave move? The motion of the medium is parallel to the direction of the wave, or back & forth Ex. Sound

8. Motion of the medium is at right angles to the direction of the wave Ex) Electromagnetic waves Don’t require a medium Motion of the medium is parallel to the direction of the wave Ex) Sound Require a medium Transverse Waves Longitudinal Waves

9. The space in the medium where the particles are crowded together The space in the medium where there are fewer particles Compression Rarefaction

10. Aim: What are characteristics of waves? Do Now: Take out a piece of loose-leaf, put your name on top & # it 1-5. Prepare for quiz. Homework: Study for Quiz & Complete questions 2 & 3 in note-packet on a separate piece of loose-leaf ***Make sure to write out the formulas, plug in #s, & give correct answer & units

11. Name_____________ What are waves? - Quiz • Waves only transfer _______________. • What type of waves require a medium? • The motion of the medium is at right angles to the direction of the wave describes a _________ type of wave. • Another name for a compressional wave is a ___________ wave. • In a Compressional wave, the space in the medium where there are fewer particles is called a _________________.

13. 1. What are the parts of a wave? A E D D C B E

14. a) Crest - b) Trough - c) Normal Resting Position - the highest point of a Transverse Wave the lowest point of a Transverse Wave position of the medium without a wave disturbance

15. What are 3 characteristics that all waves have? (D) Amplitude, (E) Wavelength, & 3. Frequency

16. 3. What is Amplitude? the maximum movement from the rest position energy =  amplitude

17. 4. What is Wavelength? the distance between 2 consecutive crests or troughs Measured in meters or cm The symbol = λ (lambda)

18. What is frequency? The number of waves that pass a point in one second b) Importance: Distinguishes one color of light from another Higher frequency = higher sound (pitch) c) Measured in units called Hertz 1 Hz = 1 wave/sec.

19. Example: You are at a lighthouse on the tip of an island. You notice that 1 wave passes every 2 seconds. What is the frequency of the wave? 1 wave/2 sec. Or = 0.5 Hz

20. 6. What is the relationship between frequency & wavelength? As Wavelength decreases, Frequency increases. As wavelength increases, Frequency decreases. Inverse Relationship

21. How do you measure wavelength? Which wave has the greatest wavelength? What is frequency? Which wave has the greatest frequency? What are the frequencies for waves A, B, C? Summary:

22. How can you calculate the speed of a wave? Recall: How is speed calculated? Wave Speed = Wavelength X Frequency or V = L*F meters X (waves) (sec)

23. Example 1: Waves pass the end of a dock 2 times every second. If the waves are 3 meters long, how fast are they moving? V L F V = L * F V = 3.0 m * 2.0 Hz V = 6 m/s

24. Example 2: A wave has a frequency of 10 Hz & a wavelength of 30 m. What is its speed? V = L * F V = 30m * 10 Hz V = 300 m/s

25. Example 3: The speed of a wave is 200 m/s, & the frequency is 20 Hz. What is its wavelength? L = V F L = 200 m/s 20 Hz L = 10 meters

26. Yahoo! Video Detail for f14transonic.mpg • Wave Parts • http://www.acs.psu.edu/users/sparrow/movies/newbackwardcomp.flat.mov

27. Aim: What does the speed of a wave depend upon? Do Now: Take out homework & prepare for quiz. Homework: Study for Quiz.

28. Quiz – Characteristics of Waves1. Write the letter that identifies: Amplitude2. Write the letter that identifies: Wavelength3. The number of waves that pass a given point in each second is known as ____________. A E B B C D E

29. The loudness of a sound is determined by its______________. (Wavelength, Frequency, or Amplitude) 5. You are at a lighthouse on the tip of an island. You notice that 15 wave passes every 3 seconds. You are at a lighthouse on the tip of an island. You notice that 15 waves passes every 3 seconds. What is the frequency of the wave?

30. What does the speed of a wave depend upon? The medium through which it travels. Recall: What is a medium?

31. 2. What are some properties of a medium which can affect the speed of sound? Density, 2. Elasticity, & 3. Temperature

32. How does density affect the speed of a wave? (Is it easier to stir a spoon through water or molasses? Why?) Waves move slower in a denser medium Due to: More mass in a given volume & More inertia to overcome Recall – What is inertia?

33. How does elasticity affect wave speed? (Is it easier to run on the beach, or on a track?) Elasticity = the ability of a medium to return to its original (resting) position Waves move faster in more elastic mediums

34. What phase of matter is the most elastic? Solids are more elastic than liquids & Liquids are more elastic than gases

35. How does temperature affect the speed of sound? Lower temperature = slower speed of sound Higher temperature = faster speed of sound Direct Relationship Why?

36. Summary: In what medium does sound travel the fastest? The slowest? Why?

37. Aim: What are 4 types of wave interactions? Do Now: Prepare for Quiz. Homework: Study for Quiz & Read pages 327 – 329 & 339, Answer Ques. #1 on pg 343

38. 1. What is A2. B3. C4. D5. G6. What type of wave is this? A D B F C G E

39. 7. The number of waves that pass a point in one second is known as __________. 8. What types of waves require a medium? 9. As temperature increases, the speed of a wave __________. 10. What do waves transfer?

40. Bonus: What is the relationship between wavelength & frequency?

41. 1. What do you know about waves traveling in the same medium? They move at a constant speed & They move in a constant (same) direction

42. 2. What happens when a wave hits an obstacle, a different medium, or another wave? Reflection Diffraction 3. Refraction (with or without dispersion) Interference

43. What causes a Reflection? a) The bouncing back of a wave when it hits a barrier b) Surfaces reflect light waves at the same angle at which they are hit. c) Examples: Looking in a mirror, or an echo

44. Reflection

45. 4. What is the Law of Reflection? angle of incidence = angle of reflection or Angle I = Angle R Example: If the angle of incidence = 30° the angle of reflection = _______

46. 5. What is Diffraction? The bending of waves around an obstacle

49. Draw This Picture

50. 6. What is Refraction? The change in direction and speed of waves when they move from one medium to another