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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

Waves

http://ngsir.netfirms.com/

slide2
Wave
  • Rhythmic disturbance that carries energy through matter or space.
types of waves
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
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
wave properties
Wave Properties
  • Amplitude
    • Displacement from position of rest
    • Depends on how wave is generated
    • More “work” gives a larger amplitude
wave properties1
Wave Properties
  • Wavelength
    • Distance of one wave from similar points (crest to crest or trough to trough)
    • Represented with λ
wave properties2
Wave Properties
  • Period
    • The time it takes for one wavelength to pass
    • Represented with T, measured in seconds
wave properties3
Wave Properties
  • Frequency
    • Number of oscillations the wave makes each second.
    • Measured in hertz (Hz)
wave properties4
Wave Properties
  • Speed
    • Depends on the material the wave is traveling through
    • Speed = λf
interference
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
types of interference
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
standing waves
Standing Waves
  • When waves’ reflections interfere constructively with each other.
    • Node – doesn’t move at all
    • Antinode – sees the largest displacement
resonance

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
sound
Sound
  • Sound waves
    • Pressure variation transmitted through matter.
    • Speed depends on the material traveling through
loudness
Loudness
  • Depends on the amplitude of the pressure wave.
  • Remember more amplitude = more energy
pitch

http://www.youtube.com/watch?v=ngk-ECb8ccQ

Pitch
  • Related to the frequency of the vibration
doppler shift

http://www.youtube.com/watch?v=Y5KaeCZ_AaY

http://www.youtube.com/watch?v=Djz_rtnXSfY

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

http://www.youtube.com/watch?v=UzI1z0u_700

Electromagnetic Spectrum
  • Visible light is only one small part of the broad spectrum of electromagnetic waves.
light1
Light
  • What we see as “white light” is actually a combination of all colors at once.

Name that band and album.

perceiving colors
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.
polarization
Polarization
  • Light (ER) vibrates in two directions. Polarizing filters reduce the motion in one of the directions.
polarization1

http://www.olympusmicro.com/primer/lightandcolor/polarization.htmlhttp://www.olympusmicro.com/primer/lightandcolor/polarization.html

http://www.sunglasswarehouse.com/thesunauthority/polarization-test

Polarization
reflection

http://www.youtube.com/watch?v=LTWHxZ6Jvjs

Reflection
  • Law of Reflection
    • Angle of Incidence equals Angle of Reflection
reflection1
Reflection
  • Regular Reflection
    • Smooth Surface
reflection2
Reflection
  • Diffuse Reflection
    • Rough Surface
    • Light is scattered
refraction

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
angle of refraction
Angle of Refraction
  • The angle that a refracted wave makes with the normal
critical angle
Critical Angle
  • The incident angle that will cause a reflected ray to lie along the boundary of a surface.
total internal reflection
Total Internal Reflection
  • Angle at which the ray is reflected back into the medium
diffraction

http://www.falstad.com/ripple/

http://w ww.gcsescience.com/pwav44.htm

Diffraction
  • Bending of a wave around an obstacle
dispersion
Dispersion
  • The separation of light into its colors
objects vs images
Objects vs. Images
  • Object – the source of diverging light waves
  • Image – the light that is viewed
plane mirror
Plane Mirror
  • Smooth flat surface
virtual image
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.
concave mirrors
Concave Mirrors
  • Curved inward
  • Principle axis – straight line to the surface at the center
concave mirrors1
Concave Mirrors
  • Focal point – where the parallel rays meet after reflecting.
    • Remember: Angle of incidence equals angle of reflection!
concave mirrors2
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.
concave mirrors3
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.
convex mirrors
Convex Mirrors
  • Spherical – reflects light from the outer surface.
  • Rays always diverge – no real images produced.
lenses
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

convex lens
Convex Lens
  • Thicker at the center than at the edges
    • Also known as converging lens
concave lens
Concave Lens
  • Thinnest in the center
    • Also known as a diverging lens
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