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Waves Sound and Light

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					Waves, Sound, and Light

        Chapter 3
         Bell Work 11/29/10
Please get a new bell work sheet. Write
   each statement then decide if they are
   true or false, if false correct them.
1. Mechanical waves transfer energy
   through a vacuum.
2. A wave is a disturbance that transfers
   energy.
3. An example of a longitudinal wave is a
   water wave.
           Light 3.1 Vocab
Electromagnetic wave – a disturbance that
  transfers energy through a field

Radiation – energy that moves in the form
 of EM waves
 How EM waves form and sources
         of EM waves
• Electric and magnetic fields make up EM
  waves
• Many of the EM waves on Earth’s
  environment come from the Sun.
• Stars give off EM waves but since they are
  so far away not many of their waves hit the
  Earth
• Technology is also a source of EM waves
      Bell Work 11/30/10
1. What are the two types of
   fields that make up an EM
   wave?
2. How are EM waves used to
   measure distances in space?
3. How does microwave cooking
   depend on reflection?
  Electromagnetic spectrum
• The range of all EM frequencies
• The spectrum goes from the lowest
  frequencies to the highest
  frequencies
• Higher-frequency EM waves with
  more electromagnetic vibrations per
  second have more energy than lower-
  frequency EM waves
    Measuring EM Waves

• EM wave frequency is
  measured in hertz (Hz)
• One hertz equals one cycle
  per second
            Radio waves
• Have the longest wavelengths, the lowest
  frequencies, and the lowest energies

• Examples of radio waves are AM/FM radio
  and broadcast television
               Microwaves
• EM waves with shorter wavelengths, higher
  frequencies, and higher energy than other
  radio waves
• Radar – radio detection and ranging. Used to
  control air traffic at airports, analyze weather
  conditions and measure the speed of a
  moving vehicle
• Radar led to the invention of microwave
  ovens
• Cell phones – radio transmitter and receiver
  that uses microwaves
         Bell work 11/25/09
1. List the colors of the visible light
   spectrum in order from longest
   wavelength to shortest wavelength.



2. What are the 7 parts of the
   electromagnetic spectrum?
          Bell Work 11/30/09
Please use complete sentences

1. Give an example of using a radio wave.

2. Give an example of using a microwave.

3. Give an example of using an x-ray.
        Bell Work 12/1/09
1. What do electromagnetic waves
   transfer energy through?

2. What is radiation?

3. How does a microwave cook
   food?
            Visible Light
• The part of the EM spectrum that human
  eyes can see.
• Longest wavelengths are red all the way to
  violet
• ROY G BIV
• Red, Orange, Yellow, Green, Blue, Indigo,
  Violet
             Bell Work 12/2/09
1. What are EM waves measured in?

2. Give two examples of using a radio wave.

3. Give 3 examples of using a microwave.

4. List the colors of visible light from longest
   wavelength to shortest wavelength.
            Infrared Light
• Type of EM wave most often associated
  with heat
• Sometimes referred to as heat rays
• You can feel it as warmth coming from the
  sun, a fire, or a radiator
• Infrared lamps are used to provide warmth
  in bathrooms and to keep food warm after
  its been cooked
• Some animals can see in infrared light
              Ultraviolet Light
• Has more energy than visible light
• The waves in this range can damage your skin and
  eyes
• Sun block and UV-protection sunglasses are
  designed to filter out the higher frequencies
• UV light can be used to sterilize medical instruments
  and food by killing harmful bacteria
• IV light causes skin cells to produce vitamin D which
  is essential to good health
• UV light is visible to some animals. Bees and some
  other insects
                 X-rays
• Has a very high frequency and energy
• Pass easily through soft tissues of the
  body, but are absorbed by the bone
• The x-rays pass through exposing the film
  where there is no bone
• When getting x-rays other parts of the
  body are covered with a lead vest to block
  the x-rays
              Gamma rays
• Highest frequencies and energies of any
  EM waves
• Produced by some radioactive substances
  as well as the sun and other stars
• Gamma rays can penetrate the soft and the
  hard tissues of the body, killing normal cells
  and causing cancer cells to develop
• Gamma rays can also be used to kill
  cancer cells and fight tumors
         Bell Work 12/3/09
1. Which group from the EM spectrum has
   the highest frequencies?
2. Which group pass easily through soft
   tissues of the body, but are absorbed
   by the bone?
3. What can you use to filter out the high
   frequencies of UV rays?
4. Which EM wave is most associated with
   heat?
       Bell Work 12/4/09

Predict what would happen if
  you kept a green plant in the
  dark for one month. Explain
  why. (at least 3 sentences)
             Vocab 3.3
Incandescence – the production of
  light by materials at high
  temperatures

Luminescence – the production of
 light without the high temperature.
 Many organisms produce their own
 visible light through this.
Bioluminescence – production of
 light by living organism. These
 organism produce light from
 chemical reactions rather than
 intense heat.

Fluorescence – occurs when a
 material absorbs EM radiation of
 one wavelength and gives off EM
 radiation of another.
         Bell Work 12/5/09
1. What happens to the speed of EM waves
   in a vacuum?

2. What happens when microwaves
   encounter water?

3. What produces the most EM waves on
   Earth?
          Light 3.4 Notes
Transmission – the passage of an
 EM wave through a medium.

• If the light reflected from objects
  did not pass through the air,
  windows, or most of the eye, we
  could not see the objects
Absorption – the
 disappearance of an EM
 wave into the medium

• Absorption affects how things
  look, because it limits the light
  available to be reflected or
  transmitted
  How Materials Transmit Light
• Transparent materials allow most of
  the light that strikes them to pass
  through.
• Translucent materials transmit some
  light, but they also cause it to spread
  out in all directions.
• Opaque materials do not allow any
  light to pass through them, because
  they reflect light, absorb light, or both
Scattering – the spreading out of light rays
 in all directions, because particles reflect
 and absorb the light

• Fog or dust in the air, mud in water, and
  scratches or smudges on glass can all
  cause scattering

• Scattering creates a glare and makes it
  hard to see even through a transparent
  material
Polarization – a quality of light in which
  all of its waves vibrate in the same
  direction
• Polarizing filters reduce glare and make
  it easier to see objects

Prism – a tool that uses refraction to
  spread out the different wavelengths
  that make up white light
• Prisms split light into colors by refracting
  wavelengths in different amounts
  Color Reflection and Absorption
The color of an object or material is
  determined by two factors

1. the wavelengths it absorbs and
   those it reflects

2. The wavelengths present in the light
   that shines on the object
• A material that reflects all wavelengths
  of visible light appears white

• A material that absorbs all
  wavelengths of visible like appears
  black

• A green lime absorbs most
  wavelengths but reflects green, so the
  lime looks green
     Primary Colors of Light
• The human eye can detect only 3
  color bands: red, green, and blue
• Your brain perceives these three
  colors and various mixtures of them
  as all the colors
Primary colors – red, green, and blue
  – can be mixed to produce all the
  possible colors
         Primary Pigments
• Materials can be mixed to produce
  colors just as light can

• Materials that are used to produce
  colors are called pigments

Primary pigments – cyan, yellow, and
 magenta
          Bell Work 12/8/09
1. What color is something that absorbs all
   the colors?
2. What color is something that reflects all
   colors?
3. If an object absorbs most wavelengths
   but reflects violet what color will it be?
 Bell Work 12/9/09 – (fill in the blanks)
1. Bioluminescent animals produce light
   through _________.
2. When light is absorbed into a medium, the
   waves ________ in the medium.
3. The primary pigments create colors through
   _____________ mixing.
4. An electromagnetic wave transfers energy
   through a ______.
5. Most of the visible EM waves on Earth
   come from the ______.

				
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