Light and Sound

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Light and Sound

• 4th Grade Science

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EQ What is light?

• Its a kind of energy called electromagnetic
  (EM) radiation (but this kind of radiation is
  not harmful).
• There are other kinds of EM radiation too
  (radio waves, microwaves, x-rays, etc.), but
  light is the part WE can see, the part that makes
  the rainbow.

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How does light travel?

• FAST and STRAIGHT
• About 186,000 miles per second , so light from
  the sun takes about 8 minutes to go 93 million
  miles to earth.
• If you could DRIVE to the sun at 60 mph , it
  would take you 177 years to get there! In one
  second, light can go around the earth 7 times!

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How are shadows formed?

• When light strikes an object, some light
  reflects. When there is an obstacle in the way of
  the light, and it cannot pass, there is no light
  to reflect, and thus a shadow is formed.
• A SHADOW IS FORMED WHEN LIGHT SHINES AT AN OPAQUE
  OBJECT BLOCKING THE LIGHT RAY CAUSING A SHADOW
  BECAUSE LIGHT ONLY GOES IN A STRAIGHT LINE.

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Vocabulary

•  Transparent object is one that lets
  light pass through.   (clear window)
• Translucent objects lets some light go through
  but not all  (bathroom window)
• opaque light can not go through it. Impenetrable
  by light neither transparent nor translucent.
• Example opaque object lets no light pass
  through-( table)
• absorption refers to the physical process
  of absorbing light. The process in which incident
  radiated energy is retained without reflection or
  transmission on passing through a medium. 
• For example, light can not go through an
  object that is opaque because that
  object absorbs the light.

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Refraction

• http//ilovenewton.com/wp-content/uploads/2012/05/
  interference_refraction_reflection-300x225.jpg

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Sound energy

•  Sound is a type of energy made by vibrations.
  When any object vibrates, it causes movement in
  the air particles. These particles bump into the
  particles close to them, which makes them vibrate
  too causing them to bump into more air particles.
  This movement, called sound waves, keeps going
  until they run out of energy. If your ear is
  within range of the vibrations, you hear the
  sound.
• Pitch the frequency at which an object vibrates
  to create a sound.
• A tuning fork, for example, that
  vibrates 440 times a second will produce a
  perfect A note. It is these predetermined
  levels of frequencies that pitch is categorized
  into the twelve chromatic musical tones.

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vibrate   move back and forth rapidly.

• Did you hear that sound? It was made by air
  vibrating. The same is true for sounds made by
  musical instruments. The difference between NOISE
  and MUSIC is that musical sounds are organized
  into patterns that have pitch and rhythm. Noise
  is just random, disorganized sounds. Sounds are
  made and travel in the same way whether they are
  musical sounds or noise.
• A musical sound is called a tone, and is produced
  by air vibrating a certain number of times per
  second. These vibrations are called waves.

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EQ What is sound?

• Sound is a form of energy, just like electricity
  and light. Sound is made when air molecules
  vibrate and move in a pattern called waves, or
  sound waves.
• Think of when you clap your hands, or when you
  slam the car door shut. That action produces
  soundwaves, which travel to your ears and then to
  your brain, which says, I recognize that sound.
• This is from Science Kids at Home.

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SOUND

• Sound is a type of energy made by vibrations.
  When any object vibrates, it causes movement in
  the air particles. These particles bump into the
  particles close to them, which makes them vibrate
  too causing them to bump into more air particles.
  This movement, called sound waves, keeps going
  until they run out of energy. If your ear is
  within range of the vibrations, you hear the
  sound.
• Picture a stone thrown into a still body of
  water. The rings of waves expand indefinitely.
  The same is true with sound. Irregular repeating
  sound waves create noise, while regular repeating
  waves produce musical notes.
• When the vibrations are fast, you hear a high
  note. When the vibrations are slow, it creates a
  low note. The sound waves in the diagram show the
  different frequencies for high and low notes.
• Low frequency notes High frequency notes

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Low Frequency Notes
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High Frequency Notes
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Quiz

• The bending of a wave caused by the change of
  speed that occurs when the wave passes from one
  medium into another is __________.
• 2. The bouncing back of a wave off an object or
  surface is ______________.

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• 3. Describes materials that let nearly all the
  light rays that hit them pass through
  _______________.
• 4. Describes materials that let some light rays
  pass through but scatter some of the other rays
  is ________.
• 5. Describes materials that do not let any light
  pass through them ______

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Directions Put a T for true and an F for false

• ___ Light is electromagnetic radiation.
• ___ Opaque objects can either absorb or reflect
  light.
• ___ Transparent substances reflect light.
• ___ A convex lens is curved outwards.
• ___ A prism is a type of lens
• ___ You can see your reflection on an opaque
  object
• ___ The visible spectrum is light you can see.
• ___ All light passes through translucent objects.
• ___ A concave lens is like the inside of a
  sphere.
• ___ Refraction means the light stops.

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answers

• T
• T
• F
• T
• F
• F
• T
• F
• T
• F