2 What can happen to incoming light TransmittedGlassReflected (including scattering)Silver, waterHave them think of examples.absorbedBlack pavementOr any partial combination of these things
3 Materials and LightThere are three different types of materials that light will or will not pass through.TransparentTranslucentOpaque
4 Transparent LightMaterials 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 MaterialsClear glassClean waterClear 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 MaterialsThin fabricsFrosted glassThin paper
8 Light cannot pass through these material Opaque MaterialsLight cannot pass through these material
9 Examples of Opaque Materials BrickMetalThick paperAluminum FoilWoodStones
10 ACTIVITY Why is wax paper translucent? Why is transparent tape called transparent tape
11 AnswerAns 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!
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 boxAperture – A hole through which lightenters the camera.Shutter – A way to control how longlight enters the box.Lens – A way of focusing light for asharp image.Viewfinder – A way to aim the camera.Film Holder – A way to hold the filmin 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 sideBrass shim stock10mm pinPencilEmery paperElectrical tapeUtility knifeFoamcoreMrs. 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 Tape5” x 6” RectangleFold the strips up and tape.
21 The Front of the CameraIn 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 CameraLay 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”Rectangle4” 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 apertureemery paper an abrasive paper used for sandingfoamcore lightweight material made of three layers – tag board, foam, tag boardpaper negative uses photography paper to create a reversed image which light areas appear dark and dark areas appear lightpierce to make a hole throughphotographic paper is paper coated with light sensitive chemicalspinhole camera a camera that uses a pinhole instead of a lensshutter 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 EvaluationPrecutMatt BoardTake picturesusingExposure TableFill in the Steps-in-Process Chart
27 Self Evaluation Answers Precutmatt boardConstructcamera backCut hole forapertureDrill pinholeand attachto cameraTape box toprevent lightfrom enteringConstructcamera boxTake picturesusingExposure TableMake shutterTapephotographicPaper to backof cameraHow did you do?
28 Straight surfaces may look curved if the film plane is curved.
30 What is a mirror?Since silver is such a good reflector a coating of silver on glass - a good (common) mirrorIf 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 mirrorA half-silvered mirror used with proper lighting can show objects on one side or the other of the mirror
31 Plane MirrorsPlane mirrors are a flat sheet of glass, that has a silver-colored coating on one sidethe coating reflects the lightThe coating is smooth = regular reflection occurs and a clear image formsImage is a copy of an object formed by reflected or refracted rays of light
32 The Plane MirrorA 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.reflectionrefractionabsorptionWaterAir
34 How Images FormLight rays from the object strike the mirror and reflect towards the observer’s eyeEven though rays are reflected the observer’s brain treats them as if they had come from behind the mirrorImage appears to be behind the mirror