Table of Contents Light and Color Reflection and Mirrors Refraction and Lenses Seeing Light Using Light

When Light Strikes an Object - Light and Color When Light Strikes an Object When light strikes an object, the light can be reflected, transmitted, or absorbed.

The Color of Objects - Light and Color The color of an opaque object is the color of the light it reflects.

The Color of Objects - Light and Color The color of a transparent or translucent object is the color of the light it transmits.

Combining Colors - Light and Color As pigments are added together, fewer colors of light are reflected and more are absorbed.

Building Vocabulary - Light and Color Using a word in a sentence helps you think about how best to explain the word. After you read the section, carefully note the definition of each Key Term. Also note other details in the paragraph that contain the definition. Use all this information to write a sentence for each Key Term. Key Terms: Examples: primary colors secondary color complementary colors pigment Key Terms: Examples: transparent material Three colors that can combine to make any other color are called primary colors. A transparent material transmits most of the light that strikes it. translucent material Two primary colors combine in equal amounts to produce a secondary color. A translucent material scatters light as it passes through. opaque material An opaque material reflects or absorbs all of the light that strikes it. Any two colors that combine to form white light are called complementary colors. Pigments are colored substances that are used to color other materials.

Click the Video button to watch a movie about color. - Light and Color Color Click the Video button to watch a movie about color.

Click the SciLinks button for links on colors. - Light and Color Links on Colors Click the SciLinks button for links on colors.

End of Section: Light and Color

Reflection of Light Rays - Reflection and Mirrors Reflection of Light Rays The two ways in which a surface can reflect light are regular reflection and diffuse reflection.

Concave Mirrors - Reflection and Mirrors A mirror with a surface that curves inward like the inside of a bowl is a concave mirror.

Concave Mirrors - Reflection and Mirrors Ray diagrams show where an image forms and the size of the image. The steps below show how to draw a ray diagram.

Concave Mirrors - Reflection and Mirrors Concave mirrors can form either virtual images or real images.

Convex Mirrors - Reflection and Mirrors A mirror with a surface that curves outward is called a convex mirror.

Mirrors Activity - Reflection and Mirrors Click the Active Art button to open a browser window and access Active Art about mirrors.

Comparing and Contrasting - Reflection and Mirrors Comparing and Contrasting As you read, compare and contrast concave and convex mirrors in a Venn diagram like the one below. Write the similarities in the space where the circles overlap and the differences on the left and right sides. Concave Mirror Convex Mirror Real images Virtual images Curves outward Enlarged images Reduced images Curves inward

End of Section: Reflection and Mirrors

Bending Light - Refraction and Lenses The index of refraction of a medium is a measure of how much light bends as it travels from air into the medium. The table shows the index of refraction of some common mediums.

Bending Light - Refraction and Lenses Interpreting Data: Which medium causes the greatest change in the direction of a light ray? Diamond causes the greatest change in the direction of a light ray traveling from air.

Bending Light - Refraction and Lenses Interpreting Data: According to the table, which tends to bend light more: solids or liquids? According to the graph, most solids bend light more than liquids do (quartz is an exception).

Bending Light - Refraction and Lenses Predicting: Would you expect light to bend if it entered corn oil at an angle after traveling through glycerol? Explain. You would not expect light to bend if it entered corn oil at an angle after traveling through glycerol, because corn oil and glycerol have the same value for the index of refraction.

Refraction of Light - Refraction and Lenses When light rays enter a medium at an angle, the change in speed causes the rays to bend or change direction.

Lenses - Refraction and Lenses A lens is a curved piece of glass or other transparent material.

Lenses - Refraction and Lenses An object’s position relative to the focal point determines whether a convex lens forms a real image or a virtual image.

Lenses - Refraction and Lenses A concave lens can produce only virtual images because parallel light rays passing through the lens never meet.

Lenses Activity - Refraction and Lenses Click the Active Art button to open a browser window and access Active Art about lenses.

Asking Questions - Refraction and Lenses Before you read, preview the red headings. In a graphic organizer like the one below, ask a what, when, where, or how question for each heading. As you read, write answers to your questions. Question Answer When does refraction occur? When light rays enter a medium at an angle What are the types of lenses? Concave and convex lenses

End of Section: Refraction and Lenses

Correcting Vision - Seeing Light Concave lenses are used to correct nearsightedness. Convex lenses are used to correct farsightedness.

Sequencing - Seeing Light Sequence is the order in which the steps in a process occur. As you read, make a flowchart that shows how you see objects. Put the steps of the process in separate boxes in the order in which they occur. How You See Objects Light enters the eye. Light focuses on the retina. An image forms. Rods and cones send signals to the brain.

Click the PHSchool.com button for an activity about eyesight. - Seeing Light More on Eyesight Click the PHSchool.com button for an activity about eyesight.

End of Section: Seeing Light

Optical Instruments - Using Light A telescope forms enlarged images of distant objects. Telescopes use lenses or mirrors to collect and focus light from distant objects.

Optical Instruments - Using Light A microscope uses a combination of lenses to produce and magnify an image.

Optical Instruments - Using Light The lens of the camera focuses light to form a real, upside-down image on film in the back of the camera.

- Using Light Lasers Laser light consists of light waves that all have the same wavelength, or color. The waves are coherent, or in step.

Optical Fibers - Using Light The floodlight in the swimming pool gives off light rays that travel to the surface. If the angle of incidence is great enough, a light ray is completely reflected back into the water. This complete reflection of light by the inside surface of a medium is called total internal reflection.

Optical Fibers - Using Light Optical fibers can carry a laser beam for long distances because the beam stays totally inside the fiber as it travels.

Building Vocabulary - Using Light A definition states the meaning of a word or phrase by telling about its most important feature or function. Carefully read the definition of each Key Term. Then write a definition of each Key Term in your own words. Key Terms: Key Terms: Examples: microscope camera laser hologram optical fiber Key Terms: Examples: total internal reflection Examples: telescope A microscope is an instrument that forms enlarged images of tiny objects using lenses. A telescope is a device that uses lenses or mirrors to collect and focus light from distant objects. The total internal reflection is the complete reflection of light by the inside surface of a medium. refracting telescope A refracting telescope is a telescope that uses convex lenses to focus light. A camera is a device that uses lenses to focus light on film to record an image. objective A laser is a device that produces an intense beam of coherent light. An objective is the large lens in a telescope or microscope that gathers and focuses light. eyepiece An eyepiece is the lens near the eye in a telescope or microscope that magnifies the image. A hologram is a three-dimensional photograph created by a laser. reflecting telescope A reflecting telescope is a telescope that uses a concave mirror to gather light. An optical fiber is a strand of glass or plastic that can carry light long distances.

Click the SciLinks button for links on lasers. - Using Light Links on Lasers Click the SciLinks button for links on lasers.

End of Section: Using Light

Graphic Organizer Type of Mirror Effect on Light Rays Type of Image Plane Regular reflection Virtual Concave Converge Real or virtual Convex Spread out Virtual Type of lens Effect on Light Rays Type of Image Convex Converge Real or virtual Concave Spread out Virtual

End of Section: Graphic Organizer