Light

Light and Color

Reflection and Mirrors

Refraction and Lenses

Seeing Light

Using Light

Table of Contents

Light - Light and Color

When Light Strikes an ObjectWhen light strikes an object, the light can be reflected, transmitted, or absorbed.

Light - Light and Color

The Color of ObjectsThe color of an opaque object is the color of the light it reflects.

Light - Light and Color

The Color of ObjectsThe color of a transparent or translucent object is the color of the light it transmits.

Light

Primary Colors of LightWhen we combine the three primary colors of light in equal amounts, white light is produced.

Light - Light and Color

Combining ColorsAs pigments (inks, paints, etc.) are added together, fewer colors of light are reflected and more are absorbed. The color you see is the result of the colors a particular pigment reflects.

Light

Building VocabularyUsing 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.

- Light and Color

Key Terms: Examples:

transparent material A transparent material transmits most of the light that strikes it.

translucent material A translucent material scatters light as it passes through.

opaque material An opaque material reflects or absorbs all of the light that strikes it.

Key Terms: Examples:

primary colors

secondary color

complementary colors

pigment

Three colors that can combine to make any other color are called primary colors.Two primary colors combine in equal amounts to produce a secondary color.Any two colors that combine to form white light are called complementary colors.Pigments are colored substances that are used to color other materials.

Light

End of Section:Light and Color

Light

Light - Reflection and Mirrors

Reflection of Light RaysThe two ways in which a surface can reflect light are regular reflection and diffuse reflection.

Light

Mirror Images• A plane mirror is a flat sheet of glass that has a smooth,

silver colored coating on one side. • This coating reflects an upright and same sized virtual

image or something that does not really exist.

Light - Reflection and Mirrors

Concave Mirrors• A mirror with a surface that curves inward like the inside of a bowl is a

concave mirror.• The optical axis represents an imaginary line that divides the mirror in

half and focal point is where the parallel light rays intersect.

Light - Reflection and Mirrors

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

Light - Reflection and Mirrors

Concave Mirrors• Concave mirrors can form either virtual images or real images. • Real images form when rays actually meet at the focal point, are

upside down, and may be smaller or larger than the actual object.

• Virtual images appears to be behind the mirror, is upright, and is always larger than the original object

Light - Reflection and Mirrors

Convex MirrorsA mirror with a surface that curves outward is called a convex mirror.

Light

Comparing and ContrastingAs 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 outwardEnlarged

images

Curves inward

Reduced images

- Reflection and Mirrors

Light

End of Section:Reflection and

Mirrors

Light

Bending Light

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.

- Refraction and Lenses

Light

Bending Light

Diamond causes the greatest change in the direction of a light ray traveling from air.

Interpreting Data:

Which medium causes the greatest change in the direction of a light ray?

- Refraction and Lenses

Light

Bending Light

According to the graph, most solids bend light more than liquids do (quartz is an exception).

Interpreting Data:

According to the table, which tends to bend light more: solids or liquids?

- Refraction and Lenses

Light

Bending Light

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.

Predicting:

Would you expect light to bend if it entered corn oil at an angle after traveling through glycerol? Explain.

- Refraction and Lenses

Light - Refraction and Lenses

Refraction of LightWhen light rays enter a medium at an angle, the change in speed causes the rays to bend or change direction.

Light

RainbowsWhite light separates into different colors on entering the raindrop due to dispersion, causing red light to be refracted less than blue light.

Light

MiragesA mirage is a naturally occurring optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky.

Light - Refraction and Lenses

LensesA lens is a curved piece of glass or other transparent material.

Light - Refraction and Lenses

LensesAn object’s position relative to the focal point determines whether a convex lens forms a real image or a virtual image.

Light - Refraction and Lenses

LensesA concave lens can produce only virtual images because parallel light rays passing through the lens never meet.

Light

Asking QuestionsBefore 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.

When does refraction occur?

When light rays enter a medium at an angle

What are the types of lenses?

Concave and convex lenses

Question Answer

- Refraction and Lenses

Light

End of Section:Refraction and

Lenses

Light

Anatomy of the Human Eye

Light - Seeing Light

Correcting VisionConcave lenses are used to correct nearsightedness. Convex lenses are used to correct farsightedness.

Light

SequencingSequence 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.

- Seeing Light

Light

End of Section:Seeing Light

Light - Using Light

Optical InstrumentsA telescope forms enlarged images of distant objects. Telescopes use lenses or mirrors to collect and focus light from distant objects.

Light - Using Light

Optical InstrumentsA microscope uses a combination of lenses to produce and magnify an image.

Light - Using Light

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

Light - Using Light

LasersLaser light consists of light waves that all have the same wavelength, or color. The waves are coherent, or in step.

Light

HologramsA hologram is a 3-D photograph created by using the light from a laser.

Light - Using Light

Optical FibersThe 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.

Light - Using Light

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

Light

Building Vocabulary

- Using Light

Key Terms: Examples:telescope A telescope is a device that uses lenses or mirrors to

collect and focus light from distant objects.refracting telescope A refracting telescope is a telescope that uses

convex lenses to focus light.objective 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.reflecting telescope A reflecting telescope is a telescope that uses a

concave mirror to gather light.

Key Terms: Examples:microscope

camera

laser

hologram

optical fiber

A microscope is an instrument that forms enlarged images of tiny objects using lenses.A camera is a device that uses lenses to focus light on film to record an image.A laser is a device that produces an intense beam of coherent light.A hologram is a three-dimensional photograph created by a laser.An optical fiber is a strand of glass or plastic that can carry light long distances.

Key Terms: Examples:total internal reflection The total internal reflection is the complete reflection

of light by the inside surface of a medium.

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.

Light

End of Section:Using Light

Light

Graphic Organizer

Virtual

Type of Mirror Effect on Light Rays Type of Image

Type of lens Effect on Light Rays Type of Image

Plane Regular reflection

Real or virtual

Convex Spread out

Convex

Virtual

Concave Converge

Virtual

Converge Real or virtual

Concave Spread out

Light

End of Section:Graphic Organizer