Waves
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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/


Waves

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


Parts of longitudinal waves

Parts of Longitudinal Waves


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


Doppler effect in light

Doppler Effect in Light


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.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.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


Fiber optic cable

Fiber Optic Cable


Mirages

Mirages


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


Why is the sky blue

Why is the Sky Blue?


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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