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Waves

Waves. http://ngsir.netfirms.com/. Wave. Rhythmic disturbance that carries energy through matter or space. Types of Waves. Mechanical Waves Require a medium Electromagnetic Waves Move because of an electromagnetic force field; don’t need a medium. Types of Mechanical Waves. Transverse

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Waves

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  1. Waves http://ngsir.netfirms.com/

  2. Wave • Rhythmic disturbance that carries energy through matter or space.

  3. Types of Waves • Mechanical Waves • Require a medium • Electromagnetic Waves • Move because of an electromagnetic force field; don’t need a medium.

  4. Types of Mechanical Waves • Transverse • Vibration is perpendicular to the direction of wave movement • Longitudinal • Vibration is parallel to wave motion. • Surface Waves • Have characteristics of both

  5. Wave Properties • Amplitude • Displacement from position of rest • Depends on how wave is generated • More “work” gives a larger amplitude

  6. Wave Properties • Wavelength • Distance of one wave from similar points (crest to crest or trough to trough) • Represented with λ

  7. Parts of Longitudinal Waves

  8. Wave Properties • Period • The time it takes for one wavelength to pass • Represented with T, measured in seconds

  9. Wave Properties • Frequency • Number of oscillations the wave makes each second. • Measured in hertz (Hz)

  10. Wave Properties • Speed • Depends on the material the wave is traveling through • Speed = λf

  11. Interference • The result of having two waves in the same place at the same time • Also known as superposition • The waves will either combine or cancel each other out

  12. Types of Interference • Destructive Interference – amplitudes are displaced in opposite directions, so they cancel each other out when meeting. • Constructive Interference – amplitudes in same direction; add together

  13. Standing Waves • When waves’ reflections interfere constructively with each other. • Node – doesn’t move at all • Antinode – sees the largest displacement

  14. http://www.youtube.com/watch?v=hiHOqMOJTH4 http://www.youtube. com/watch?v=zpUL6sZs6J4 http://www.youtube.com/watch?v=nO0bSSXmr1A Resonance • the tendency of a system to oscillate with greater amplitude at some frequencies than at others

  15. Sound • Sound waves • Pressure variation transmitted through matter. • Speed depends on the material traveling through

  16. Loudness • Depends on the amplitude of the pressure wave. • Remember more amplitude = more energy

  17. http://www.youtube.com/watch?v=ngk-ECb8ccQ Pitch • Related to the frequency of the vibration

  18. http://www.youtube.com/watch?v=Y5KaeCZ_AaY http://www.youtube.com/watch?v=Djz_rtnXSfY Doppler Shift

  19. Doppler Effect in Light

  20. Light • We refer to light as the part of the electromagnetic spectrum that is visible to our eyes.

  21. http://www.youtube.com/watch?v=UzI1z0u_700 Electromagnetic Spectrum • Visible light is only one small part of the broad spectrum of electromagnetic waves.

  22. Light • What we see as “white light” is actually a combination of all colors at once. Name that band and album.

  23. Perceiving Colors • The color you see on an object is actually being absorbed by the object – what reaches our eye is everything BUT that color.

  24. Polarization • Light (ER) vibrates in two directions. Polarizing filters reduce the motion in one of the directions.

  25. http://www.olympusmicro.com/primer/lightandcolor/polarization.htmlhttp://www.olympusmicro.com/primer/lightandcolor/polarization.html http://www.sunglasswarehouse.com/thesunauthority/polarization-test Polarization

  26. http://www.youtube.com/watch?v=LTWHxZ6Jvjs Reflection • Law of Reflection • Angle of Incidence equals Angle of Reflection

  27. Reflection • Regular Reflection • Smooth Surface

  28. Reflection • Diffuse Reflection • Rough Surface • Light is scattered

  29. http://homepage.usask.ca/~dln136/refraction/pages/first_intro.htmlhttp://homepage.usask.ca/~dln136/refraction/pages/first_intro.html http://www.youtube.com/watch?v=Bf1k9-4bb4w Refraction • The bending of light waves at a boundary between two different media

  30. Angle of Refraction • The angle that a refracted wave makes with the normal

  31. Critical Angle • The incident angle that will cause a reflected ray to lie along the boundary of a surface.

  32. Total Internal Reflection • Angle at which the ray is reflected back into the medium

  33. Fiber Optic Cable

  34. Mirages

  35. http://www.falstad.com/ripple/ http://w ww.gcsescience.com/pwav44.htm Diffraction • Bending of a wave around an obstacle

  36. Dispersion • The separation of light into its colors

  37. Why is the Sky Blue?

  38. Objects vs. Images • Object – the source of diverging light waves • Image – the light that is viewed

  39. Plane Mirror • Smooth flat surface

  40. Virtual Image • The point that the eye interprets the light rays as having come from • In a plane mirror, the image is the same size and distance from the mirror as the object is.

  41. Concave Mirrors • Curved inward • Principle axis – straight line to the surface at the center

  42. Concave Mirrors • Focal point – where the parallel rays meet after reflecting. • Remember: Angle of incidence equals angle of reflection!

  43. Concave Mirrors • Focal length – distance from the focal point to the mirror • Real Image – light rays actually converge at that point (not virtual). Projected image.

  44. Concave Mirrors • Magnification – the ratio of the size of the image to the size of the object. • Inside the focal point – forms enlarged virtual images. • Outside the focal point – forms smaller virtual images that are upside-down.

  45. Convex Mirrors • Spherical – reflects light from the outer surface. • Rays always diverge – no real images produced.

  46. Lenses • Made of a transparent material with a refractive index greater than air. • Remember: • Transparent – light goes through uninterrupted (clear glass) • Translucent – light goes through, but is scattered so image is not easily seen (frosted glass) • Opaque – no light goes through

  47. Convex Lens • Thicker at the center than at the edges • Also known as converging lens

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