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Bellringer

Bellringer. What is electromagnetic induction?. Introduction to Waves. Surf’s up dude!. Objectives. Learn the basic characteristics of waves and use them to solve simple problems. Missing Labs. If you didn’t turn in the “Mapping Magnets” lab you have zero. Turn them in ASAP!

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Bellringer

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  1. Bellringer • What is electromagnetic induction?

  2. Introduction to Waves Surf’s up dude!

  3. Objectives • Learn the basic characteristics of waves and use them to solve simple problems.

  4. Missing Labs • If you didn’t turn in the “Mapping Magnets” lab you have zero. • Turn them in ASAP! • If you need to collect more data see me at some point today so we can figure out when will work.

  5. What Are Waves? • A wave is a disturbance that carries energy through matter or space without transferring matter. • Wave Demo

  6. Ocean Waves

  7. Wave Characteristics • Amplitude: The greatest distance from equilibrium. • The bigger the amplitude of the wave, the more energy the wave has.

  8. Wave Characteristics • Crest: The top point of a wave. • Trough: The bottom point of a wave.

  9. Wave Characteristics • Wavelength: The shortest distance between points where the wave pattern repeats itself. Wavelength is measured in meters, the symbol is

  10. Wave Characteristics • Phase: Any two points on a wave that are one or more whole wavelengths apart are said to be “in phase”.

  11. Wave Characteristics • Frequency: Is the number of complete oscillations a point on that wave makes each second. Frequency is measured in Hertz (Hz), its units are

  12. Wave Characteristics • Speed: The speed or velocity of a wave is how fast the energy is moved. For most waves, wave speed does not depend on amplitude, frequency, or wavelength. Speed depends only on the medium through which it moves.

  13. Wave Characteristics • Period: The time it takes a wave to go through one cycle, or the time it takes a point to go through one phase of the wave. • The period of a wave is measured in seconds, and it’s symbol is “T”.

  14. Examples • How does the speed of a wave change if the amplitude is increased? • The speed doesn’t change. • What is the velocity of a wave that has a frequency of 100Hz and a wavelength of 2.0m?

  15. Practice • On page 393 of the textbook answer questions 15, 16, 17, 19, 22, and 24.

  16. Answers • 15. 343m/s, 2.29x10^-3s, 0.787m • 16. You should shake it at a lower frequency because wavelength varies inversely with frequency. • 17. 2.45m/s • 19. 2.50m • 22. The frequency is one-half of its original value. • 24. The wavelength increases to 1.5 times its original value.

  17. Bellringer • What does a wave transfer? • Energy, NOT MASS! DO WORK STOP

  18. Objectives • Review and solidify the material you learned and practiced yesterday. • Learn about the different types of waves. • Study, create, and destroy different wave types.

  19. Practice • On page 393 of the textbook answer questions 15, 16, 17, 19, 22, and 24.

  20. Answers • 15. 343m/s, 2.29x10^-3s, 0.787m • 16. You should shake it at a lower frequency because wavelength varies inversely with frequency. • 17. 2.45m/s • 19. 2.50m • 22. The frequency is one-half of its original value. • 24. The wavelength increases to 1.5 times its original value.

  21. Art Time – Example Part Two • Draw two more cycles of the red wave.

  22. Art Time – Example Part Two • Draw one more cycles of the blue wave.

  23. Art Time – Example Part Two • What is the wavelength of the red wave? • 2.0m

  24. Art Time – Example Part Two • What is the wavelength of the blue wave? • 4.0m

  25. Art Time – Example Part Two • What is the amplitude of the red wave? • 0.5m

  26. Art Time – Example Part Two • What is the amplitude of the blue wave? • 0.25m

  27. Art Time – Example Part Two • If this is a snapshot of how far each wave traveled in 1 second, what is the frequency of the red wave? • 3.0Hz

  28. Art Time – Example Part Two • If this is a snapshot of how far each wave traveled in 1 second, what is the frequency of the blue wave? • 1.5Hz

  29. Art Time – Example Part Two • Are the red and blue wave in phase with each other? • Nope

  30. Art Time – Example Part Two • Mark two spots on each wave that are in phase with each other.

  31. Practice • Draw the following waves on the same graph: • A wave with an amplitude of 6m and a wavelength of 3m. • A wave with an amplitude of 2m and a wavelength of 2m. • A wave with an amplitude of 3m and a wavelength of 4m. • Which wave has the greatest frequency if they’re all traveling at the same speed?

  32. Types of Waves • There are two types of waves! • Transverse Waves: A wave that disturbs the particles in the medium perpendicular to the direction of the wave’s travel. • Longitudinal Waves: A wave that disturbs the particles in the medium parallel to the direction of the wave’s travel.

  33. Transverse vs. Longitudinal Waves

  34. Slinky Demo • How can a single transverse wave pulse be produced using a slinky? • How can a single longitudinal wave pulse be produced using a slinky? • Sound waves are longitudinal waves because they shake the air as they transfer the energy to our ears.

  35. Must Watch Television • https://www.youtube.com/watch?v=XFF2ECZ8m1A

  36. Bellringer • What is the speed of a radio wave that has wavelength of 1,396m and a frequency of 214,899.7135Hz? DO WORK STOP

  37. Objectives • Learn about the different types of waves. • Study, create, and destroy different wave types.

  38. Grade Update • Answer these questions. • How did you follow your plan on how to improve your grade? • Are you happy with your grade and what do you want your grade to be by the end of the quarter? • What are you going to do to improve your grade?

  39. Waves at Boundaries • What does the surface of water look like when you drop a small rock in a calm bucket of water? • What happens when the wave hits the walls? • Splash Demo!!! Get your goggles!

  40. Waves at Boundaries • Recall that a wave’s speed depends on the medium it passes through: • Water depth • Air temperature • Tension, and mass • A “Boundary” is when a wave goes from one medium to another.

  41. Waves at Boundaries • There are three ways you’ll be interested in at boundaries. • Incident Wave: A wave pulse that strikes the boundary. • Reflected Wave: A wave that bounces backwards after hitting the boundary. • Transmitted Wave: A wave that continue forward after hitting the boundary.

  42. Waves at Boundaries

  43. Waves at Boundaries Demos • Different Medium Demo: • The incident energy is split between reflected and transmitted energy. • Rigid Boundaries Demo: • All of the incident energy is turned into reflected energy.

  44. Checkpoint • How does the amplitude (energy) of a wave change when it hits a rigid boundary like a wall? • How is the conservation of energy observable with a single wave hitting a different medium?

  45. Waves in a Bucket • What happens if you drop two rocks into a calm bucket of water instead of just one? • Splash Demo 2.0!!! Get dem goggles back! • The waves seem to hit each other, but then just continue on their way…weird?

  46. Wave Interference • When we had two particles (carts) and pushed them into each other they collided and then stopped. • When waves collide they temporarily interfere with one another, but they do not stop each other.

  47. Wave Interference • 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.

  48. Superposition (Interference)

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