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Table of Contents

Table of Contents. What Are Waves? Properties of Waves Interactions of Waves Seismic Waves. Waves Examples: What causes them? When do they stop? What do they travel through? Do they all need a medium?. One Way to Classify Waves. Mechanical Waves Must have a medium

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Table of Contents

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  1. Table of Contents • What Are Waves? • Properties of Waves • Interactions of Waves • Seismic Waves

  2. Waves • Examples: • What causes them? • When do they stop? • What do they travel through? • Do they all need a medium?

  3. One Way to Classify Waves • Mechanical Waves • Must have a medium • Can travel at any speed • Ex: • Electromagnetic Waves • Do NOT need a medium • Travel at the speed of light • Ex:

  4. - What Are Waves? Mechanical Waves and Energy • Waves travel through water, but they do not carry the water (or the duck) with them.

  5. - What Are Waves? Transverse Waves • Waves that move the medium at right angles to the direction in which the waves travel are called transverse waves.

  6. - What Are Waves? Longitudinal Waves • Longitudinal waves move the medium parallel to the direction in which the waves travel.

  7. - What Are Waves? Longitudinal Waves • The compressions of a longitudinal wave correspond to the crest of a transverse wave. The troughs correspond to rarefactions.

  8. - What Are Waves? Transverse vs. Longitudinal Waves • Click on the link to see how the differ waves travel or propogate. • Another link with animation

  9. - Properties of Waves Amplitude, Wavelength, and Frequency • The basic properties of all waves are amplitude, wavelength, and frequency.

  10. The speed of a wave on a rope is 50 cm/s and its wavelength is10 cm. What is the wave’s frequency? Read and Understand What information have you been given? Speed = 50 cm/s Wavelength = 10 cm - Properties of Waves Calculating Frequency

  11. The speed of a wave on a rope is 50 cm/s and its wavelength is10 cm. What is the wave’s frequency? Plan and Solve What quantity are you trying to calculate? The frequency of a wave = __ Hz What formula contains the given quantities and the unknown quantity? Frequency = Speed/Wavelength Perform the calculation. Frequency = Speed/Wavelength= 50 cm/s/10 cm Frequency = 5/s= 5 Hz - Properties of Waves Calculating Frequency

  12. The speed of a wave on a rope is 50 cm/s and its wavelength is10 cm. What is the wave’s frequency? Look Back and Check Does your answer make sense? The wave speed is 50 cm per second. Because the distance from crest to crest is 10 cm, five crests will pass a point every second. - Properties of Waves Calculating Frequency

  13. Practice Problem A wave has a wavelength of 2 mm and a frequency of 3 Hz. At what speed does the wave travel? (2 mm)(3 Hz) = 6 mm/s - Properties of Waves Calculating Frequency

  14. Practice Problem The speed of a wave on a guitar string is 142 m/s and the frequency is 110 Hz. What is the wavelength of the wave? (142 m/s)/(110 Hz) = 1.3 m - Properties of Waves Calculating Frequency

  15. - Properties of Waves Outlining Properties of Waves • An outline shows the relationship between main ideas and supporting ideas. As you read, make an outline about the properties of waves that you can use for review. Use the red headings for the main ideas and the blue headings for the supporting ideas. • Amplitude • Amplitude of Transverse Waves • Amplitude of Longitudinal Waves • Wavelength • Frequency • Speed

  16. End of Section:Properties of Waves

  17. - Interactions of Waves Reflection • When an object or wave hits a surface through which it cannot pass, it bounces back.

  18. Reflection • Reflection is when waves, whether physical or electromagnetic, bounce from a surface back toward the source. A mirror reflects the image of the observer. NORMAL

  19. - Interactions of Waves Refraction • When a wave enters a new medium at an angle, one side of the wave changes speed before the other side, causing the wave to bend.

  20. Refraction • Refraction is when waves, whether physical or electromagnetic, are deflected when the waves go through a substance. The wave generally changes the angle of its general direction.

  21. - Interactions of Waves Diffraction • When a wave moves around a barrier or through an opening in a barrier, it bends and spreads out.

  22. Diffraction • Diffraction is when a wave goes through a small hole and has a flared out geometric shadow of the slit. • a characteristic of waves of all types • We can hear around a corner because of the diffraction of sound waves. For instance, if a wall is next to you when you yell, the sound will parallel the wall. The wall may stop, but the voice doesn't; sound will almost turn the corner of the wall.

  23. The interference that occurs when waves combine to make a wave with a smaller amplitude is called destructive interference. - Interactions of Waves Interference • The interference that occurs when waves combine to make a wave with a larger amplitude is called constructive interference. Link to animation of interference and standing waves. Another cool animation!

  24. - Interactions of Waves Wave Interference Double Slit experiment: https://www.youtube.com/watch?v=Kdi4e76UvO8

  25. - Interactions of Waves Standing Waves • If the incoming wave and a reflected wave have just the right frequency, they produce a combined wave that appears to be standing still. • ex: Jump rope https://www.youtube.com/watch?v=no7ZPPqtZEg

  26. - Interactions of Waves Asking Questions • Before you read, preview the red headings. In a graphic organizer like the one below, ask a what, how, when, or where question for each heading. As you read, write answers to your questions. Question Answer Waves are reflected when they hit a surface through which they cannot pass and bounce back. How are waves reflected? The bending of waves due to a change in speed What is refraction? When a wave moves around a barrier or through an opening in a barrier When does diffraction occur? A wave that appears to stand in one place even though it is really two waves interfering What is a standing wave?

  27. End of Section:Interactions of Waves

  28. Graphic Organizer Waves can be can be Transverse Longitudinal contain contain contain contain Crests Troughs Compressions Rarefactions

  29. End of Section:Graphic Organizer

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