2. Waves* A vibration or disturbance that transmits energy without transmitting matterA vibration or disturbance that transmits energy without transmitting matter http://www.e-prolab.com/comlab/overview/video/wav-t-trans.gif

3. Mechanical Waves* Waves that need a medium or material to transmit energy (water waves, sound waves, etc.)Waves that need a medium or material to transmit energy (water waves, sound waves, etc.) Waves

4. Electromagnetic Waves* Waves that can transmit energy without a medium or material to travel through (light waves, heat waves, any waves in space, etc.)Waves that can transmit energy without a medium or material to travel through (light waves, heat waves, any waves in space, etc.) http://www.thebrain.mcgill.ca/flash/capsules/images/outil_bleu16_img01.jpg

5. Cutnell & Johnson, Wiley Publishing, Physics 5 th Ed. LONGITUDINAL WAVES* Waves in which the medium vibrates parallel to the direction of wave travelWaves in which the medium vibrates parallel to the direction of wave travel http://www.gcse.com/waves/images/longitudinal.gif

6. LONGITUDINAL WAVES* Rarefaction areas where the medium is spread outareas where the medium is spread outCompression areas where the medium is pushed togetherareas where the medium is pushed together http://www.gcsescience.com/pwav7.htm

7. LONGITUDINAL WAVES The wavelength can be measured as the distance between the center of two compressionsThe wavelength can be measured as the distance between the center of two compressions Examples of longitudinal wavesExamples of longitudinal waves 1. Sound. 2. P waves from earthquakes Longitudinal Waves

8. TRANSVERSE WAVES* Waves in which the medium vibrates perpendicular to the direction of wave travelWaves in which the medium vibrates perpendicular to the direction of wave travel Cutnell & Johnson, Wiley Publishing, Physics 5 th Ed. www.physics.ohio-state.edu/ ~phys133/demo/

9. TRANSVERSE WAVES Most other types of waves are transverse (electromagnetic waves, s waves from earthquakes, etc.)Most other types of waves are transverse (electromagnetic waves, s waves from earthquakes, etc.) Transverse Waves

10. AMPLITUDE (A)* measured from the peak (or trough) to the mid-pointmeasured from the peak (or trough) to the mid-point the maximum displacement from the average positionthe maximum displacement from the average position proportional toproportional to how much energy the wave has http://www.gcsescience.com/pwav7.htm

11. WAVELENGTH (λ)* the distance between two peaks or the distance between two troughsthe distance between two peaks or the distance between two troughs the distance the wave has traveled during one complete cyclethe distance the wave has traveled during one complete cycle measured in metersmeasured in meters http://www.gcsescience.com/pwav7.htm Copywrited by Holt, Rinehart, & Winston

12. FREQUENCY (f)* the number of complete cycles in one secondthe number of complete cycles in one second Hertz is the unit of frequency (symbol Hz).Hertz is the unit of frequency (symbol Hz). http://www.gcsescience.com/pwav7.htm

13. PERIOD (T)* the time taken for one complete cyclethe time taken for one complete cycle unit is secondsunit is seconds http://www.gcsescience.com/pwav7.htm

14. Wave Speed Equation* Speed is the frequency multiplied by the wavelength, unit of meter/secondSpeed is the frequency multiplied by the wavelength, unit of meter/second

15. Wave Problem A sound wave has a frequency of 3250 Hz and a wavelength of 0.1 m. What is its velocity?A sound wave has a frequency of 3250 Hz and a wavelength of 0.1 m. What is its velocity? Source: http://www.gcsescience.com/pwav7.htm

16. What type of wave is an ocean wave? A.Transverse B.Longitudinal C.Combination of Both

17. Ocean Waves are neither transverse nor longitudinal but a combinationare neither transverse nor longitudinal but a combination Water molecules move in nearly circular pathsWater molecules move in nearly circular paths includes both a transverse and longitudinal componentincludes both a transverse and longitudinal component Cutnell & Johnson, Wiley Publishing, Physics 5 th Ed. http://www.onr.navy.mil/focus/ocean/motion/waves1.htm http://www.blueyonder.com/features/landlubbers-guide.html http://www.onr.navy.mil/focus/ocean/motion/waves1.htm

18. Ray An arrow drawn on a diagram to show the direction of propagation (movement) of a set of wavesAn arrow drawn on a diagram to show the direction of propagation (movement) of a set of waves A ray is always at 90° to the wavefrontA ray is always at 90° to the wavefront

19. Why do you hear an echo if you yell in a canyon? What is the phenomena behind both of these?What is the phenomena behind both of these? Why do you see an image of yourself when you look in a mirror?

20. Reflection of Waves* Law of Reflection When a wave reaches the boundary between two media, some or all of the wave bounces back into the first mediumWhen a wave reaches the boundary between two media, some or all of the wave bounces back into the first medium The angle of incidence is equal to the angle of reflection.The angle of incidence is equal to the angle of reflection. http://library.thinkquest.org/26162/fig3-1.gif

21. Reflection of Waves All waves can be reflected.All waves can be reflected. A wave is reflected at the boundary of the medium through which it is traveling or at any point where there is a change in the wave velocity.A wave is reflected at the boundary of the medium through which it is traveling or at any point where there is a change in the wave velocity. Cutnell & Johnson, Wiley Publishing, Physics 5 th Ed. Reflection

22. Wave Terminology Copywrited by Holt, Rinehart, & Winston

23. How could you tell if the end of a rope is fixed or not if you could not see the other end? If the rope is attached, a wave would? A. reflect back on the same side as it was transmitted (in phase). B. Reflect back on the opposite side as it was transmitted (out of phase) C. Would not reflect back Copywrited by Holt, Rinehart, & Winston

24. Reflections of waves* at a Fixed Endat a Fixed End A phase change occursA phase change occurs at a Free Endat a Free End No phase change occursNo phase change occurs www.physics.ohio-state.edu/ ~phys133/demo/

25. Reflection at a Point where the Wave Velocity Changes When there is a change of medium the speed of the wave changesthe speed of the wave changes some of the energy of the incident wave is reflected and some is transmittedsome of the energy of the incident wave is reflected and some is transmitted

26. A stiff spring is attached to the end of a slinky, if a wave is sent through the stiff spring what will happen at the junction with the slinky? A.All of the wave will be reflected back B.None of the wave will be reflected back C.Some of the wave will be reflected back and the reflected part will be in phase. D.Some of the wave will be reflected back and the reflected part will be out of phase. How is this like the fixed/loose end result?

27. Reflection at a Point where the Wave Velocity Changes* When v 2 > v 1 Transmitted wave, no phase change.Transmitted wave, no phase change. Reflected wave, phase change.Reflected wave, phase change. http://www.saburchill.com/physics/chap04.html http://www.physicsclassroom.com/Class/sound/u11l5b.html

28. Reflection at a Point where the Wave Velocity Changes* When v 2 < v 1 Transmitted wave, no phase change.Transmitted wave, no phase change. Reflected wave, no phase change.Reflected wave, no phase change. http://www.saburchill.com/physics/chap04.html

29. Refraction* When waves travel across a boundary between two different media, their speed changes.When waves travel across a boundary between two different media, their speed changes. The change in speedThe change in speed results in a change in direction of the waves. of the waves. Refraction

30. Refraction http://science.uniserve.edu.au/school/curric/stage6/phys/communicates/Student_section/student_physics/physics_pics/animated_refraction2.gif http://www.studentxpress.ie/educ/physics/physics3/refrac1.gif

31. Hall Wanderer Question If you are standing in the hall beside a classroom door, can you hear the teacher inside the class? a.Yes b.No How is this possible? Cutnell & Johnson, Wiley Publishing, Physics 5 th Ed.

32. Diffraction Diffraction occurs when waves spread out after passing through a gap or round an obstacle. Sea wave diffraction

33. Diffraction becomes more significant when the size of the gap or obstacle is reduced compared with the wavelength of the wave.

34. Diffraction* The phenomena when waves are obstructed by obstacles or pass through small openingsThe phenomena when waves are obstructed by obstacles or pass through small openings All (two or three dimensional) waves exhibit diffractionAll (two or three dimensional) waves exhibit diffraction The magnitude of these effects depends on the wavelength of the waves (more obvious when the obstacle is similar to the wavelength)The magnitude of these effects depends on the wavelength of the waves (more obvious when the obstacle is similar to the wavelength) http://physics.nad.ru/Physics/1wavedif.gif Diffraction

35. Diffraction Diffraction by a ‘large’ objectDiffraction by a ‘large’ object Diffraction by a ‘small’ objectDiffraction by a ‘small’ object http://physics.nad.ru/Physics/1wavedif.gif http://www.saburchill.com/physics/chap04.html

36. Diffraction Diffraction at a ‘large’ apertureDiffraction at a ‘large’ aperture Diffraction by a ‘narrow’ apertureDiffraction by a ‘narrow’ aperture http://physics.nad.ru/Physics/1wavedif.gif http://www.saburchill.com/physics/chap04.html

37. Boundaries and Waves Incident Wave: wave that strikes the boundary Reflected Wave: wave that returns in the larger spring For a wall boundary, if little energy is transmitted into the wall the wave may have the same amplitude, but be inverted

38. Superposition of Waves The principle of superposition states that the displacement of a medium caused by two or more waves is the algebraic sum of the displacements caused by the individual waves.The principle of superposition states that the displacement of a medium caused by two or more waves is the algebraic sum of the displacements caused by the individual waves. Two are more waves can combine to form a new wave.Two are more waves can combine to form a new wave.

39. Wave Interference The result of the superposition of two or more waves is called interference.The result of the superposition of two or more waves is called interference. Constructive interference occurs when the waves are in sync (in phase), and they combineConstructive interference occurs when the waves are in sync (in phase), and they combine Destructive interference occurs when the waves are out of sync, and the cancel some or all of each other out.Destructive interference occurs when the waves are out of sync, and the cancel some or all of each other out.

40. Constructive Interference

41. Destructive Interference

42. Interference a wave consists of many separate oscillations which are out of phase with each other The actual phase difference between two oscillations depends on the distance between them Interference

43. Interference* Two sets of waves of the same frequency traveling through the same medium: The combined effect of the two waves at a given point in the medium will depend on the phase difference between their oscillations at that pointThe combined effect of the two waves at a given point in the medium will depend on the phase difference between their oscillations at that point The two waves are said to interfere constructively or destructivelyThe two waves are said to interfere constructively or destructively

44. Constructive Interference* arrive in phase with each other.arrive in phase with each other. The resultant amplitude of these two oscillations will be equal to sum of the amplitudes of the two original oscillations.The resultant amplitude of these two oscillations will be equal to sum of the amplitudes of the two original oscillations. http://www.saburchill.com/physics/chap04.html

45. Destructive Interference* arrive out of phase with each other.arrive out of phase with each other. The resultant amplitude of the oscillations is equal to the algebraic sum of the two oscillations (smaller)The resultant amplitude of the oscillations is equal to the algebraic sum of the two oscillations (smaller) If the amplitudes of the two oscillations are equal the result is no oscillationIf the amplitudes of the two oscillations are equal the result is no oscillation http://www.saburchill.com/physics/chap04.html

46. Principle of Superposition of Waves The resultant amplitude can be found by adding together the individual amplitudes.The resultant amplitude can be found by adding together the individual amplitudes. Copywrited by Holt, Rinehart, & Winston Cutnell & Johnson, Wiley Publishing, Physics 5 th Ed. Interference

47. Principle of Superposition of Waves* For two wave sources vibrating in phase: A difference in path lengths that is zero or an integer number (1,2,3…) results in constructive interferenceA difference in path lengths that is zero or an integer number (1,2,3…) results in constructive interference Cutnell & Johnson, Wiley Publishing, Physics 5 th Ed.

48. Principle of Superposition of Waves* For two wave sources vibrating in phase: A difference in path lengths that is a half integer number (½,1½, 2½…) results in destructive interferenceA difference in path lengths that is a half integer number (½,1½, 2½…) results in destructive interference Cutnell & Johnson, Wiley Publishing, Physics 5 th Ed.

49. Interference Patterns Interference can be observed in all types of waves.Interference can be observed in all types of waves. The diagrams represent the interference pattern due to two sets of water waves of identical frequency, produced by point sources which are oscillating in phase with each other.The diagrams represent the interference pattern due to two sets of water waves of identical frequency, produced by point sources which are oscillating in phase with each other. Waves from source 1 Waves from source 2 Interference Pattern of higher frequency oscillations

50. http://www.calvin.edu/~lmolnar/anim/circ1.gif Interference Patterns 2 identical waves  Double amplitude of the wave http://www.calvin.edu/~lmolnar/anim/circ2.gif

51. Interference Patterns Offset waves  Areas of constructive and destructive interference http://www.calvin.edu/~lmolnar/anim/circ3.gif

52. Interference Patterns Wider spacing of sources- more lines of interference http://www.calvin.edu/~lmolnar/anim/circ4.gif

53. Interference Patterns The overlap of two sound wavesThe overlap of two sound waves C= compressionC= compression R = rarefactionR = rarefaction Red dot – constructive interferenceRed dot – constructive interference White dot – destructive interferenceWhite dot – destructive interference Cutnell & Johnson, Wiley Publishing, Physics 5 th Ed. Copywrited by Holt, Rinehart, & Winston

54. Standing Waves* Reflection of waves at certain frequencies produce areas of constructive and destructive interferenceReflection of waves at certain frequencies produce areas of constructive and destructive interference Appears to be stationaryAppears to be stationary Nodes = areas where medium has no amplitudeNodes = areas where medium has no amplitude Anti-nodes = areas of maximum amplitudeAnti-nodes = areas of maximum amplitude

55. Standing Waves http://www.hamline.edu/~arundqui/phys1140/animations/standingwave.gif http://www.calvin.edu/~lmolnar/anim/sw.gif