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Wave Review

Learn about the characteristics of waves, different types of waves, wave speed, frequency, and amplitude, as well as wave interactions such as transmission, reflection, refraction, and diffraction. Discover the concept of resonance and the Doppler effect. Explore practical applications of waves in various fields.

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Wave Review

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  1. Wave Review

  2. If a vibrational disturbance occurs, energy travels/propagates out in all directions from the vibrational source. 1 disturbance = pulse

  3. Oscillators generate continuous waves • Many pulses = continuous wave.

  4. Traveling waves (as opposed to standing waves) transfer energy! Matter is not transferred by waves Give example of how we know E gets transferred.

  5. Wave Vocabulary • Points in Phase. • 1 cycle passes in time = 1 period • f = cycles passing per sec Hz • Medium – matl wave travels through. l crests Equilibrium

  6. 1. The wave below shows a “snapshot” that lasted 4.0 seconds. What is the frequency of the wave? 4.0 seconds 2 cycles/4 s = 0.5 Hz

  7. Transverse Waves • Earthquake S waves, EM waves.

  8. Longitudinal/CompressionalParticles compressed and expanded parallel to energy propagation. • Compressions – high P, density • Rarefactions- low P, density. • Sound.

  9. All points on a wave that are inphase comprise a wave front.

  10. Rays – a ray is an arrow sketched through the wave fronts (perpendicular) to show direction of wave propagation.

  11. Wave Speed • Speed/Velocity = d/t • If a crest (or any point on a wave) moves 20m in 5 sec, • v = 20m/5s = 4 m/s. • Waves of the same type travel through homogenous materials at same speed regardless of frequency of wavelength.

  12. Relationship of wave speed to wavelength(l) and frequency(f).v = d/t but for waves d = 1l occurs in time T (1period)so v = l/Tsince freq f =1/Tv =lf

  13. 2. A machine gun fires 10 rounds/sec at 300 m/s. a. What is the distance between the bullets? b. What would happen to the distance if the firing rate were increased. • f = 10 Hz. • v = 300 m/s. • l = ? • v = fl. • l = 300 m/s / 10 s-1. • l = 30 m.

  14. Wave Speed v = lf. Depends on medium Fixed by source oscillation Depends on the others.

  15. What can happen when wave pulses or continuous waves interact? • Transmission • Superposition & Interference

  16. What happens when they pass?

  17. Superposition – combining & addition of waves.

  18. Wave Superposition/Interference Destructive Constructive

  19. Boundary Behavior • Transmission (partial or not at all), • Reflection (partial or total) • Refraction – transmission with velocity change. • Diffraction – bending around boundary.

  20. Wave hits rigid boundary: • Reflection – pulse inverts. • It comes back totally opposite.

  21. Pulse hits soft boundary?

  22. Law of reflection

  23. Refraction – D speed and bending upon entering new material. The frequency is fixed by source. Constant speed until new material.

  24. Wavefronts entering new material

  25. Diffraction – curvature through small openings (apertures) or around obstacles.

  26. Curvature vs. Opening width

  27. Diffraction around obstacle.

  28. Never a frequency change unless the vibration rate of source changes. Or --

  29. Object & observer are in relative motion.

  30. Types of Waves • Mechanical • Non-mechanical • Medium • No medium

  31. Compressional/ pressure/ longitudinal • Always mechanical. Why? Examples?

  32. Transverse Examples?

  33. Polarization Transverse Waves

  34. Deduce that for waves Wave speed • v = lf.

  35. v = d t but for waves d = 1l occurs in time T v = l/Tsince freq f =1/Tv =lf

  36. d – time graph 1 point in oscillatory motion See hamper transverse.

  37. Displ – position graph shows the displacement of every point on wave at a given time. Need to see equilibrium position. See hamper longitudinal pg 91.

  38. IB Set IB Wave Prac 1 • Read hamper 4.4

  39. Frequency and Amplitude Physical Properties

  40. For light increased amplitude increases brightness.

  41. For sound: increased amplitude increases volume.

  42. Wave frequency (f, l) Wave type for EM waves. Color for light. Sound = f pitch

  43. Doppler Effect Objects in relative motion: toward each other – frequency increases (l decreases). away – frequency decreases (l increases).

  44. Doppler • Red/Blue Shift galaxies and stars.

  45. Sound

  46. Increasing velocity Sound velocity solid liquid gas In gas hot faster. cold slower.

  47. Resonance & Sympathetic Vibration

  48. All objects have a natural frequency of vibration. Resonance- the inducing of vibrations of a natural rate by a vibrating source having the same frequency “sympathetic vibrations” System resonance – amplitude will increase.

  49. Push at natural frequency, amplitude increases

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