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Waves

This section delves into the fundamentals of waves, emphasizing their role as disturbances transferring energy through a medium. Waves are classified as either mechanical, requiring a medium for propagation, or electromagnetic, which can travel through a vacuum. Key features of waves include amplitude, wavelength, and frequency, all of which are crucial in defining their behavior. Additionally, the mechanics of transverse and longitudinal waves are explored, showcasing how these different types propagate through various substances, ultimately affecting how we perceive light and sound.

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Waves

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  1. Textbook pages 92-99 Perception of Light & Sound Waves

  2. What is a WAVE? • A disturbance that travels through a medium

  3. What is a WAVE? • A disturbance that travels through a medium • Medium: a substance that carries the disturbance from one location to another

  4. What is a WAVE? • A disturbance that travels through a medium • Medium: a substance that carries the disturbance from one location to another • How? The particles of the medium interact with particles next to them allowing the disturbance to travel • Examples of a medium • Water • Air • Ground

  5. What is a WAVE? • Transports energy from one place to another

  6. What is a WAVE? • Transports energy from one place to another

  7. What is a WAVE? • Transports energy from one place to another • Particles of the medium are only temporarily displaced from the rest position

  8. What is a WAVE? • Transports energy from one place to another • Particles of the medium are only temporarily displaced from the rest position • Does not transport matter

  9. Wave Characteristics • Propagation • Amplitude • Wavelength • Frequency

  10. Propagation • Waves are distinguished by the way they propagate through a medium

  11. Propagation • Transverse Waves • Propagates perpendicular to the motion of the medium Motion of the Medium Wave Motion

  12. Propagation • Transverse Waves CREST Equilibrium TROUGH

  13. Propagation • Longitudinal Waves • Propagates parallel to the motion of the medium Wave Motion Motion of the Medium

  14. Propagation • Longitudinal Waves • Propagates parallel to the motion of the medium Wave Motion Motion of the Medium

  15. Propagation • Longitudinal Waves • Propagates parallel to the motion of the medium Wave Motion Motion of the Medium

  16. Propagation • Longitudinal Waves • Propagates parallel to the motion of the medium Region of Compression Region of Rarefaction

  17. Amplitude (A) • Related to the amount of energy transferred by a wave

  18. Amplitude (A) • Transverse Waves • Maximum distance travelled by a particle in the medium compared to its equilibrium position Equilibrium

  19. Amplitude (A) • Transverse Waves • Depends on energy transmitted by the wave

  20. Amplitude (A) Region of low-density compression • Longitudinal Waves • How tightly the medium is pushed together at the compressions Region of High-density compression

  21. Amplitude (A) • Longitudinal Waves • Depends on the density of compression

  22. Wavelength () • Length of a wave’s complete cycle • Transverse Waves  Cycle

  23. Wavelength () • Length of a wave’s complete cycle • Longitudinal Waves  Cycle

  24. Frequency (f) • Number of cycles per unit of time • Measured in Hertz (Hz) – the number of cycles per second • 1 Hz = completes one full cycle in one second Cycle Cycle

  25. Speed at which a Wave Travels • Speed of a wave depends on • Medium it travels in • Temperature

  26. Determine the speed at which a Wave Travels • Speed = frequency x wavelength

  27. Determine the speed at which a Wave Travels • Speed = frequency x wavelength • v = f x  • v = speed (m/s) • f = frequency (Hz) •  = wavelength (m)

  28. Determine the speed at which a Wave Travels • What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz? G R A S P

  29. Determine the speed at which a Wave Travels • What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz? G R A f = 170.5Hz = 2.00m S P

  30. Determine the speed at which a Wave Travels • What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz? G R A f = 170.5Hz = 2.00m S P v = ?

  31. Determine the speed at which a Wave Travels • What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz? G R A f = 170.5Hz = 2.00m S P v = ? v = f x 

  32. Determine the speed at which a Wave Travels • What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz? G R A f = 170.5Hz = 2.00m v = (170.5Hz)(2.00m) v = 341 m/s S P v = ? v = f x 

  33. Determine the speed at which a Wave Travels • What is the speed of a sound wave that has a wavelength of 2.00m and a frequency of 170.5Hz? G R A f = 170.5Hz = 2.00m v = (170.5Hz)(2.00m) v = 341 m/s S P v = ? The speed of the sound wave is 341 m/s v = f x 

  34. Types of Waves • Mechanical Waves • Electromagnetic Waves

  35. Mechanical Waves • Can only propagate in a medium

  36. Mechanical Waves • Can only propagate in a medium • How? A disturbance changes the physical shape of the medium and passed onto neighbouring particles

  37. Mechanical Waves • Can only propagate in a medium • How? A disturbance changes the physical shape of the medium and passed onto neighbouring particles • Examples: water waves, sound waves, seismic waves

  38. Electromagnetic Waves • Can propagate in a medium and a vacuum

  39. Electromagnetic Waves • Can propagate in a medium and a vacuum • Carry Radiant Energy

  40. Electromagnetic Waves • Can propagate in a medium and a vacuum • Carry Radiant Energy • Examples: light waves in space

  41. Electromagnetic Spectrum • Categories of electromagnetic waves • Classified by frequency and wavelength

  42. Electromagnetic Spectrum Long Short High Low

  43. Electromagnetic Spectrum • Radio Waves • Smallest frequency • Invisible & transport little energy • Example: Radio, Television, Microwaves, Cellphones

  44. Electromagnetic Spectrum • Infrared • Invisible, but feel the warmth emitted • Example: Night vision goggles, short-distance communication (wireless keyboards, remote controls, etc.)

  45. Electromagnetic Spectrum • Visible Light • Only electromagnetic waves that can be seen by humans • Together, colours make up white light • Example: Photography, movies, computer screens

  46. Electromagnetic Spectrum • Ultraviolet Rays (UV) • Invisible to humans • Greater frequency, transport more energy • Responsible for suntans, but can cause cancer • Example: sterilization of surgical instruments, treatments

  47. Electromagnetic Spectrum • X-Rays • High frequency • Able to travel through media opaque in visible light • Example: baggage inspection, radiography

  48. Electromagnetic Spectrum • Gamma Rays • Highest frequency and transports the highest energy • Travel easily through matter • Can cause burns, cancer, and genetic mutations • Example: cancer treatment, food preservation

  49. Homework • Read Textbook pages 92-99 • Do Workbook pages 49-52

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