Heat, Light, and Sound

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Heat, Light, and Sound

• Chapter 18
• Mr. Saks
• General Science

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Objectives

• Identify and describe the three ways that heat
  moves.
• Identify and describe the parts of an energy
  wave.
• Identify and describe why things look the color
  they look.

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Words To Know

• amplitude The height of a wave.
• conduction The bumping of molecules that moves
  heat through matter.
• convection The transfer of heat within a gas or
  liquid by the movement of warmer particles.
• frequency The number of wave cycles that pass
  through a point in one second.
• insulator a material that does not conduct heat
  well
• prism a triangular-shaped object made of clear
  glass. It can break up a ray of white light into
  the colors of the rainbow (ROY G BIV)

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• radiation energy that can move through a vacuum
• reflection light bouncing off an object
• refraction the bending of light rays when the
  pass from one material to another
• spectrum the rainbow-like band of color that is
  seen when white light is refracted
• vacuum the absence of matter
• wavelength the distance from the crest of one
  wave to the crest of the next

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I. What is Light?

• Light is a form of energy that travels in waves
• Light always travels in a straight path
• ray one straight line of light
• Light rays travel in groups
• beams groups of traveling light rays
• Light is slowed down when traveling
• air slows light the least
• then liquid
• solids slow light the most

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• Light travels in different wavelengths
• We can only see a few wavelengths
• visible light is what we see
• Light waves are sometimes too small or long to be
  seen
• Some short waves are ultra violet light
• Some waves are too long infrared
• http//www.classzone.com/books/earth_science/terc/
  content/visualizations/es2801/es2801page01.cfm?cha
  pter_novisualization

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II. What Happens to light when it hits an object?

• Light can do 4 things when strikes objects
• Pass Through the object
• Bend when striking
• Absorbed into the object
• Bounce Off an object
• Light passes through
• Air, clear glass, clear plastic, and colorless
  liquids (water)

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• Objects that are not clear absorb the most light
  striking them
• Light passes into them, but not through
• Light absorbed is changed to heat energy
• Good absorbers are dark colors and rough surfaces
• What would you wear on a cool day to keep warm?

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• Reflection when light bounces off an object
• All materials reflects some light
• mirrors and shiny objects reflects almost all
  light
• Light reflecting off objects delivers images to
  your eyes
• a. reflected light is how we see

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• Refraction the bending of light rays
• When you stick a pole in water it appears to look
  bent
• the water bends the light rays and not the pole
  itself
• Light striking the water is slowed and bends away
  from the surface of the water
• Cause of Refraction
• a. change in the speed of the light as it passes
  from one substance to another

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III. Light and Color

• White light mixture of all the colors of the
  spectrum
• Colors of the Spectrum
• ROY G BIV
• Red, orange, yellow, green, blue, indigo, and
  violet
• Colors of an object fruits
• Chemicals absorb all the colors of the spectrum
  and reflect the color of the fruit (orange looks
  orange)
• Colors are absorbed into the fruit and turned
  into energy

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• Black objects absorb all colors of the spectrum
• Charcoal absorb all light waves
• Neon (gas) is very excitable (moves a lot)
• Pulses of electricity inside a glass tube can
  produce a lot of energy ( we see as different
  colors)
• Stars shine because the gas inside is excited and
  glows

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• Primary Colors colors that your eyes are
  sensitive to (red, green, blue)
• Green is the color that the eye is most sensitive
• Why is the sky blue when sun light is white?
• Air molecules in the sky bend traveling white
  light strikes
• Blue waves are bent the most by air molecules
• Blue waves are absent when white light arrives
• We see the sky as blue

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• Lasers are high powered electrical light beams
• only seen when some sort of powder, smoke
• concerts, dance club
• Color
• Red absorbed all colors except red
• White reflects all colors
• reflects the sun
• reflects the heat
• Black absorbs all colors from the sun
• turns wave energy into heat

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IV. Sound

• What is Sound?
• sound is another form of energy that moves in
  waves
• sounds travels a million times slower than light
  waves.
• All sounds are made of vibrations of matter

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• How Sound Works?
• When you yell across a field at a friend
• Your vocal cords vibrate
• Sound waves travel through the air
• They make air molecules vibrate
• Sound waves cause tiny bones in your ear to
  vibrate

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• Amplitude Controls the Loudness of Sound
• The amplitude in the height of the wave
• Loud sounds create BIG WAVES
• Soft sounds create tiny waves

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NOTE Sound needs molecules to travel.
SoOOOOOOO will sound travel in space? NO. because
there is a vacuum in space and nothing for the
sound waves to travel on.
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V. Heat and Temperature

• Heat is a form of Energy
• You can FEEL heat
• From the sun
• From a fire
• Heat can be found in everything, even the ocean.
  
• Why?
• 1). Everything is made of molecules.
• 2). Since molecules are always moving they
  produce heat
• 3). The faster they move the hotter the object.
• 4). Temperature is the average kinetic energy in
  something

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• SOOOOOOO! What has more kinetic energy
• (circle your choice)
• A jug of hot cider.or a cup of hot cider
• How about a cup of coffee..or.Pacific ocean
• WHY?
• The Jug and the Pacific Ocean is a lot bigger so
  they have more kinetic energy
• Heat always moves from a warmer place to a cooler
  place
• An oven heats a pizza.
• You get cold as you step outside in the winter
• your heat energy is transferring to the
  environment from your body
• Heat can move from one place to another by
  Convection, Conduction, Radiation

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• Convection How heat moves through liquids and
  gases.
• Warm gases and fluids have a lower density.
• Cool gases and fluids have a higher density
• Why your attic is hot in the summer while the
  basement is cool.
• That is why on a hot summer day we get quick rain
  storms in the afternoon.
• Air gets baked all day and superheated and rises
  rapidly in the atmosphere in the afternoon. (HOT
  AIR RISES)

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• As air is heated the molecules begin to spread
  out.this means it is less dense.
• As air is cooled the molecules begin to collapse
  together.air becomes more dense.
• Low density molecules rise.high density
  molecules sink.

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• Conduction How heat energy moves through a
  solid
• Energy moves through solids by molecules bumping
  into one another.
• Ex. Spoon in a hot cup of coffee gets hot.
• Conductors
• Things that exchange and carry heat energy
• Some things are better conductors than others
• Metals usually conduct heat well
• Paper, wood, rubber, and glass are poor conductors

Example
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• Insulators
• These are things that do not conduct energy well.
• What are some insulators and conductors in your
  house?

• Conductor

• Insulator