1. LIGHT SHADOW AND REFLECTION

2. What can happen to incoming light
Transmitted
Glass
Reflected (including scattering)
Silver, water
Have them think of examples.
absorbed
Black pavement
Or any partial combination of these things

3. Materials and Light
There are three different types of materials that light will or will not pass through.
Transparent
Translucent
Opaque

4. Transparent Light
Materials that you can see through allow almost all of the light to pass through.
Light is allowed through with very little bending or scattering of the rays of light.

5. Clear glass Clean water Clear plastic
Examples of Transparent Materials
Clear glass
Clean water
Clear plastic

6. Opaque objects do not let any light through them
Opaque objects do not let any light through them. You cannot see through them. Some examples of opaque objects are:

7. Translucent Materials
Materials that allow only some light to pass through.
Objects allow light to pass through, but they scatter the rays so much that you cannot get a clear view of what is on the other side.
Examples of Translucent Materials
Thin fabrics
Frosted glass
Thin paper

8. Light cannot pass through these material
Opaque Materials
Light cannot pass through these material

9. Examples of Opaque Materials
Brick
Metal
Thick paper
Aluminum Foil
Wood
Stones

10. ACTIVITY Why is wax paper translucent?
Why is transparent tape called transparent tape

11. Answer
Ans 1 You can see some light, but you cannot see through it.
I can barely see my leftovers wrapped in wax paper.
Ans 2 You can see through it or light rays are allowed to pass through it.
I can completely see my leftovers wrapped in transparent plastic wrap.

12. Quick Facts about Opaque Materials
These objects will cast a shadow when lit up.
Brick, metal, and thick paper stop light completely.
This is why you cannot see your leftovers wrapped in aluminum foil!

13. SHADOW

14. Specular or diffuse?
Diffuse reflection (paper) Specular reflection (mirror) Diffuse transmission (wax paper)

15. Pinhole Photography

16. What is a Pinhole Camera?
A camera without a lens which uses a very small hole pierced in one end to allow light to pass through. An upside down image is formed on the back of the camera which can be covered with photography paper or film.
Light rays from an object passes through a small hole to form an image.
(File provided by Wikimedia Commons)

17. A camera has a few simple components:
A light tight box
Aperture – A hole through which light
enters the camera.
Shutter – A way to control how long
light enters the box.
Lens – A way of focusing light for a
sharp image.
Viewfinder – A way to aim the camera.
Film Holder – A way to hold the film
in the correct place to receive the focused light.

19. Making a Pinhole Camera
To make a pinhole camera you will need the following supplies:
Matt board, black on one side
Brass shim stock
10mm pin
Pencil
Emery paper
Electrical tape
Utility knife
Foamcore
Mrs. Doering’s First Pinhole Camera

20. The Removable Camera Back
The removable back is constructed from the 5” x 6” rectangle and the 1” strips.
Centered on the back (black side), trace a 4” x 5” rectangle.
Lay the edges of the 1” strips against these lines and tape them with small pieces of electrical tape. Fold the strips up and tape the corners by folding the tape in half with the sticky side out and pressing tightly into the inside corners.
Tape all the seams to make them light tight.
1” Strips
(Gray)
Black Electrical Tape
5” x 6” Rectangle
Fold the strips up and tape.

21. The Front of the Camera
In the center of a 4” x 5” rectangle cut a small ¼” x ½” rectangle with the utility knife.
You will complete your aperture later.
Cut Opening in Center

22. The Box of the Camera
Lay the front of the camera, black side up, with the two other 4” x 5” rectangles in a line with the 4” edges touching.
Next lay the 5” x 5” squares next to the center 4” x 5” rectangle, forming a cross.
Tape the seams together.
5” x 5”
Rectangle
4” x 5”
Black Electrical Tape

23. Attach the Pinhole to the Camera
Place the brass pinhole/aperture over the open rectangle on the outside of the camera front.
Using electrical tape, attach the brass pinhole/aperture securely.
Make sure the pinhole is visible through the opening.
For a shutter, take a piece of tape and cover the hole.

24. Taking Pictures with a Pinhole Camera
In the dark room, tape photographic paper to the inside, back cover.
Go outside and aim your pinhole at the object you would like to photograph, securing your camera by setting it on something.
Open the shutter by pulling down the tape covering the pinhole/aperture.
Following the exposure table in the next slide, count the number of seconds you need the aperture to receive light.
Close the shutter.
Remove the photographic paper in the dark room and develop the paper negative.

25. Glossary aperture a hole or an opening through which light is admitted
brass shim stock a very thin piece of brass to use as the aperture
emery paper an abrasive paper used for sanding
foamcore lightweight material made of three layers – tag board, foam, tag board
paper negative uses photography paper to create a reversed image which light areas appear dark and dark areas appear light
pierce to make a hole through
photographic paper is paper coated with light sensitive chemicals
pinhole camera a camera that uses a pinhole instead of a lens
shutter is like a door that opens and closes to let light through the aperture for a determined period of time

26. Fill in the Steps-in-Process Chart
Self Evaluation
Precut
Matt Board
Take pictures
using
Exposure Table
Fill in the Steps-in-Process Chart

27. Self Evaluation Answers
Precut
matt board
Construct
camera back
Cut hole for
aperture
Drill pinhole
and attach
to camera
Tape box to
prevent light
from entering
Construct
camera box
Take pictures
using
Exposure Table
Make shutter
Tape
photographic
Paper to back
of camera
How did you do?

28. Straight surfaces may look curved
if the film plane is curved.

29. MIRROR AND REFLECTION

30. What is a mirror?
Since silver is such a good reflector a coating of silver on glass - a good (common) mirror
If the silver coating is thin enough the mirror can be made to transmit 50% of the light and to reflect the other 50%
This is called a half-silvered mirror
A half-silvered mirror used with proper lighting can show objects on one side or the other of the mirror

31. Plane Mirrors
Plane mirrors are a flat sheet of glass, that has a silver-colored coating on one side
the coating reflects the light
The coating is smooth = regular reflection occurs and a clear image forms
Image is a copy of an object formed by reflected or refracted rays of light

32. The Plane Mirror
A mirror is a highly polished surface that forms images by uniformly reflected light.
Note: images appear to be equi-distant behind mirror and are right-left reversed.

33. In the study of how light behaves, it is useful to use “light rays” and the fact that light travels in straight lines.
When light strikes the boundary between two media, three things may happen: reflection, refraction, or absorption.
reflection
refraction
absorption
Water
Air

34. How Images Form
Light rays from the object strike the mirror and reflect towards the observer’s eye
Even though rays are reflected the observer’s brain treats them as if they had come from behind the mirror
Image appears to be behind the mirror