1 / 27

Ch. 25: Waves

Ch. 25: Waves. A WAVE is a rhythmic disturbance that carries energy through matter or space. General Wave Characteristics. Mechanical Waves. Not all waves travel through a medium. Mechanical waves only transfer energy through matter . There are two types: Transverse

dian
Download Presentation

Ch. 25: Waves

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ch. 25: Waves

  2. A WAVEis a rhythmic disturbance that carries energy through matter or space

  3. General Wave Characteristics

  4. Mechanical Waves • Not all waves travel through a medium. • Mechanical waves only transfer energy through matter. • There are two types: • Transverse • Longitudinal (or compressional) • Wave motion transfers energy without transferring matter • Click here for a visual of mechanical waves (at bottom of page)

  5. Transverse Waves: matter in the medium moves perpendicular to direction the wave travels

  6. Longitudinal (Compressional) Waves: matter in the medium moves parallel to the direction the wave travels

  7. Combination Waves: Ocean Water An ocean wave is a combination of transverse and longitudinal waves. The individual particles move in ellipses as the wave disturbance moves toward the shore.

  8. Concept Check What is a wave? What are the two types of mechanical waves?

  9. Wave Properties There are four wave properties: • Amplitude • Frequency • Wavelength • Wave Velocity

  10. Amplitude is a measure of the amount of energy in a wave In Transverse Waves… In CompressionalWaves…look at how dense the compressions are. The more dense, the higher the amplitude

  11. Frequencyis the number of wavelengths that pass a fixed point each second f = waves/second SI unit = Hertz (Hz) As Frequency , Wavelength Is this a high- or low-frequency wave?

  12. Wavelength is the distance between a point on one wave and the identical point on the next wave

  13. Calculating Frequency • F = 1/T • Remember T… • Called “period” • The time it takes for one wave to pass a given point • Measured in seconds • What is the frequency of ocean waves that wash up on the shore every 2.5 seconds?

  14. Wave Velocity is how “fast” the wave moves Velocity = wavelength x frequency v = λf v = velocity (m/s) λ = wavelength (m) f = frequency (Hz)

  15. Example A sound wave travels from a speaker to your ear. If it has a frequency of 12,000 Hz and a wavelength of 2 cm, what is its velocity?

  16. Concept Check List and describe the four wave properties.

  17. How do waves differ from one another? 1) Energy, 2) Velocity, 3) Appearance TRANSVERSE VS. COMPRESSIONAL

  18. Some other terms to know… • Period • Time for one wave to pass a given point (seconds) • Inverse of frequency • Node • The point where the medium is never displaced • On the “normal” line • Antinode – • The point of maximum displacement • Occurs at the wave’s crest

  19. Standing Waves ANTINODES NODES

  20. Wave Behavior • All waves of all types exhibit these four behaviors: • Reflection • Refraction • Diffraction • Interference

  21. Reflection The “bouncing back” of a wave

  22. The Law of Reflection says… Angle of Incidence = Angle of Reflection

  23. Refraction • The change in wave direction at the boundary between two different media • Different materials allow waves to travel at different speeds • Angle of Refraction • Amount of bending • Depends on how much the material changes the wave’s speed

  24. Diffraction The bending of a wave around a barrier or a small opening It’s the same process for sound AND light

  25. Interference When two or more waves (blue and red) exist in the same medium, each wave moves as though the other were absent When they meet, they interfere with one another and make a new wave (green). Visualization of Interference

  26. Constructive or Destructive? • Constructive Interference – 2 waves combine to form a new wave with a larger amplitude. • Destructive Interference – 2 waves combine to produce a wave with a smaller amplitude.

  27. f = 1/T f = frequency (Hz) T = period (s) Wave Formulas • v = λ f • v = velocity (m/s) • λ = wavelength (m) • f = frequency (Hz)

More Related