Light Week 5 Properties of Light Lenses and Optical Tools Eye Structure and Function

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?

Property # 1: Reflection Reflection happens when light bounces off of an object.

Reflection Practice Problems

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.

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.

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.

Types of objects Transparent (light transmitted) Translucent (some light transmitted) Opaque (no light transmitted) More on Transmission

Stand Up For Your Light!

WHEN LIGHT BOUNCES OFF AN OBJECT REFLECTION

TRANSFERS LIGHT ENERGY TO THE SURROUNDING ENVIRONMENT ABSORPTION

RELEASE OF LIGHT IN ALL DIRECTIONS SCATTERING

TRANSMISSION & ABSORPTION

OCCURS WHEN LIGHT STRIKES A MATERIAL AND PASSES THROUGH IT TRANSMISSION

SCATTERING

REFLECTION

ABSORPTION

TRANSMISSION

REFLECTION

SCATTERING

REFLECTION

Bill Nye: Light Optics Take notes for EC!

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

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

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?

Catalyst: Period 4 Define each of the four properties of light. Give a real world example of each.

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

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

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).

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.

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).

Types of Lenses There are 2 types of lenses: 1. CONVEX 2. CONCAVE

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

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

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)

Examples of CONVEX lenses 1.Magnifying glass 2.Cameras 3.Telescopes 4.Our Eyes

It looks like there is a cave on both sides!! So, it must be concave!! Concave Lens A concave lens is thinner in the middle than at the edges

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

Concave Lenses and Images A concave lens produce upright images that are smaller than the real object.

Example of CONCAVE lenses Nearsighted eyeglasses (can’t see far away)

Optical Tools Using lenses in the REAL world

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

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

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

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

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

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

Analogy: The Eye as a Camera HOW DOES A CAMERA WORK? 1. Light enters the camera through the aperture 2. The lens (glass part) focuses the light. 3. The shutter lets the light pass through to the film (the black part that opens and closes when a picture is taken). 4. The focused light creates an image on film.

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.

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.

1. Cornea  Clear outer tissue that covers the eye (column A)

1. Cornea  Receives light that is reflected by an object (column B)

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

2. Pupil  Round black hole behind the cornea (column A)

2. Pupil The pupil lets light into the eye (column B)

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.

3. Iris  The colored part surrounding the black pupil (column B)

3. Iris Opens and closes the pupil to control the amount of light coming through

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.

4. Lens  Clear tissue behind the pupil and iris

4. Lens  Collects and focuses light Calf eye lens

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.

Vitreous fluid  Fluid-filled space between the lens and the retina

Vitreous fluid  Gives the eyeball its round shape

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.

5. Retina  A thin layer of tissue at the back of the eye that has light-sensing cells called rods and cones

5. Rods Rod-shaped work in dim light let you see black, gray, and white

5. Cones cone-shaped work in bright light let you see color

Investigate: After-Images

Investigate: After Images

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.

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!)

7. Optic Nerve  Located at the back of the eye

7. Optic Nerve  receives electrical signals from the retina  sends them to the brain where the final image is made

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.

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.

Brain POP The Eye

Parts of the Eye Scrambler

Cow Eye Dissection Virtual

Eye Model

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