Light Week 5

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Light Week 5

• Properties of Light
• Lenses and Optical Tools
• Eye Structure and Function

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Catalyst

1. What is the law of reflection?
2. A light ray hits a mirror with a 40 degree angle
   of incidence--what is the angle of reflection?
3. What is the difference between reflection and
   refraction?
4. What is the difference between diffuse reflection
   and regular reflection?

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Property 1 Reflection

• Reflection happens when light bounces off of an
  object.

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Reflection Practice Problems
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Property 2 Absorption

• Absorption is the transfer of light energy to its
  surrounding environment.
• Ex Hot window on a warm day
• Ex The reason why a flashlight beam gets dimmer
  is because the light gets absorbed by air
  particles.

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Property 3 Scattering

• Scattering is the release of light energy in all
  directions.
• Ex Sunlight
• Blue light is scattered the most by sunlight,
  which is why the sky looks blue.

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Property 4 Transmission

• Transmission happens when light waves strike
  something and passes through it.
• When you see through glass, it is because light
  is able to pass through the glass.

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More on Transmission

• Types of objects
• Transparent (light transmitted)
• Translucent (some light transmitted)
• Opaque (no light transmitted)

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Stand Up For Your Light!
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• WHEN LIGHT BOUNCES OFF AN OBJECT

REFLECTION
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• TRANSFERS LIGHT ENERGY TO THE SURROUNDING
  ENVIRONMENT

ABSORPTION
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• RELEASE OF LIGHT IN ALL DIRECTIONS

SCATTERING
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TRANSMISSION ABSORPTION
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• OCCURS WHEN LIGHT STRIKES A MATERIAL AND PASSES
  THROUGH IT

TRANSMISSION
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TRANSMISSION
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SCATTERING
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REFLECTION
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ABSORPTION
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ABSORPTION
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TRANSMISSION
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REFLECTION
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SCATTERING
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REFLECTION
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Bill Nye Light Optics

• Take notes for EC!

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Exit Quiz

• What is the difference between transmission,
  absorption, and scattering?
• Name one real world example for each of the four
  properties of light.

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I Can

• I CAN describe the 4 properties of light
• Reflection
• Absorption
• Scattering
• Transmission

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Catalyst Period 3

1. What is the law of reflection?
2. A light ray hits a mirror with a 40 degree angle
   of incidence--what is the angle of reflection?
3. What is the difference between reflection and
   refraction?
4. What is the difference between diffuse reflection
   and regular reflection?
5. What are the 4 properties of light?

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Catalyst Period 4

• Define each of the four properties of light. Give
  a real world example of each.

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I Can

• I CAN describe and compare and contrast convex
  and concave lenses.
• I CAN describe how lenses are used in optical
  tools
• Microscopes
• Cameras
• Telescopes

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Lens

• A lens is a curved piece of glass or other
  transparent material that refracts light.

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Focal Point and Optical Axis

• OPTICAL AXIS An imaginary line that divides a
  lens or mirror in half.
• FOCAL POINT (F) The point where light rays
  parallel to the optical axis converge (come
  together).

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Lens and Images

• A lens forms an image by REFRACTING light rays
  that pass through it.
• The type of image formed by a lens depends on the
  shape of the lens and the position of the object.

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Types of Images

• VIRTUAL IMAGE upright image that forms where
  light seems to come from (like a mirror)
• REAL IMAGE forms when light rays actually meet.
  (appears upside down).

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Types of Lenses

• There are 2 types of lenses
• CONVEX
• CONCAVE

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Convex Lens

• A convex lens or magnifying glass is thicker in
  the center than at the edges.

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Convex Lenses

• A convex lens can focus the light that enters it
  and direct it to one point.

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Convex Lenses and Images

• Depending on where you hold the lens--the image
  you see will either be right side up (real image)
  or upside down(virtual image)

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Examples of CONVEX lenses

1. Magnifying glass
2. Cameras
3. Telescopes
4. Our Eyes

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Concave Lens

• A concave lens is thinner in the middle than at
  the edges

It looks like there is a cave on both sides!! So,
it must be concave!!
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Concave lenses

• Concave lenses make light rays move away from
  each other or spread out.

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Concave Lenses and Images

• A concave lens produce upright images that are
  smaller than the real object.

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Example of CONCAVE lenses

• Nearsighted eyeglasses
• (cant see far away)

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Optical Tools

• Using lenses in the REAL world

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Camera

• A camera uses one or more lenses to focus light,
  and film to record an image.
• The lens of a camera focuses light from the
  object to form an upside-down image on the film
  in the back of a camera.

LENS focuses light.
SHUTTER controls whether light reaches film.
APERTURE controls how much light enters.
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Telescopes

• A telescope forms enlarged images of distant
  objects.
• Telescopes use combinations of lenses or mirrors
  to collect and focus light from distant objects.
• Two types REFLECTING and REFRACTING

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Microscopes

• A microscope makes small objects look larger.
• A microscope uses a combination of lenses to form
  enlarged images of tiny objects.

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Exit Quiz

• What is the difference between convex/concave
  lenses?
• Describe any two optical tools you learned about
  today.

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Catalyst

• Why is the eye important?
• How do you think it works?
• Why would we be studying the eye in a unit on
  Light?

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I Can

• I CAN identify the parts of and the function of
  the eye.
• Vocabulary

• Cornea
• Pupil
• Iris
• Retina
• Rods
• Cones
• Lens

• Optic Nerve
• Ligaments
• Aqueous humor
• Vitreous humor
• Nearsighted
• Farsighted

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Analogy The Eye as a Camera

• HOW DOES A CAMERA WORK?
• Light enters the camera through the aperture
• The lens (glass part) focuses the light.
• The shutter lets the light pass through to the
  film (the black part that opens and closes when a
  picture is taken).
• The focused light creates an image on film.

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Analogy The Eye as a Camera

• Basically, a camera lets in a certain amount of
  light, focuses the lights, and prints the image
  that the light creates onto film.

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Analogy The Eye as a Camera

• The eye is like a camera. It also lets in a
  certain amount of light, focuses the light, and
  creates an image.

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1. Cornea

• Clear outer tissue that covers the eye (column A)

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1. Cornea

• Receives light that is reflected by an object
  (column B)

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1. Cornea

• Analogy to the camera Lens (Column D)
• The cornea is like the outer lens because it
  receives light and sends it to where it needs to
  go

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2. Pupil

• Round black hole behind the cornea (column A)

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2. Pupil

• The pupil lets light into the eye (column B)

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2. Pupil

• Analogy to the camera Aperture (Column D)
• The pupil is like the aperture because it helps
  to control how much light enters the eye.

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3. Iris

• The colored part surrounding the black pupil
  (column B)

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3. Iris

• Opens and closes the pupil to control the amount
  of light coming through

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3. Iris

• Analogy to the camera Shutter (Column D)
• The iris is ALSO like the shutter because it
  helps to control how much light enters the eye.

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4. Lens

• Clear tissue behind the pupil and iris

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4. Lens

• Collects and focuses light

Calf eye lens
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4. Lens

• Analogy to the camera Lens (Column D)
• The lens of the eye is ALSO like the lens of a
  camera because it receives light (from the pupil)
  and focuses the lights.

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Vitreous fluid

• Fluid-filled space between the lens and the retina

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Vitreous fluid

• Gives the eyeball its round shape

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Vitreous fluid

• Analogy to the camera Empty space between the
  lens and the film (Column D)
• The vitreous fluid is the empty space between the
  lens and the film because that is the space that
  light needs to travel through to reach its final
  destination.

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5. Retina

• A thin layer of tissue at the back of the eye
  that has light-sensing cells called rods and cones

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5. Rods

• Rod-shaped
• work in dim light
• let you see black, gray, and white

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5. Cones

• cone-shaped
• work in bright light
• let you see color

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Investigate After-Images
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Investigate After Images
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After-Images Explained

• The ghostly birds are called afterimages. An
  afterimage is an image that stays with you even
  after you have stopped looking at something.
• As you stare at the red bird, light-sensitive
  cells at the back of your eyes become less
  responsive to red light. When you shift your gaze
  to the birdcage, your visual system subtracts red
  light from the white light that is being
  reflected from the white background.
• White light minus red light is blue-green light.
  That is why the afterimage of the parrot is
  blue-green.

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6. Retina

• Analogy to the camera Film (Column D)
• The retina is like the film because this is where
  light produces a rough image (but not the final
  image!)

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7. Optic Nerve

• Located at the back of the eye

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7. Optic Nerve

• receives electrical signals from the retina
• sends them to the brain where the final image is
  made

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7. Optic Nerve

• Analogy to the camera Journey that you walk when
  you take your film to the lab to get developed
  (Column D)
• The optic nerve is the journey because this is
  the path that the light/electrical signals take
  to become a final picture!
• The brain is like the lab that develops the
  picture.

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Wow, that was a lot of info!Quick review

• A camera takes in light, focuses light, and
  creates an image.
• An eye is like a camera because it also takes in
  light, focuses light, and creates an image.
• Light travels through the cornea, pupil, iris,
  lens, vitreous space, retina, and optical nerve.

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Brain POP

• The Eye

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Parts of the Eye

• Scrambler

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Cow Eye Dissection

• Virtual

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Eye Model
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Exit Quiz

• What are the seven parts of the eye that light
  hits in order?
• How does the eye act like a camera?