Table of Contents Reflection and Mirrors 9.2 Ms. De Los Rios 7 th Grade Waves and Light

Types of Waves The electromagnetic spectrum includes many kinds of waves. Identify each kind of wave on the electromagnetic spectrum. What is the name of the highest energy waves? Waves of the Electromagnetic Spectrum

Vocabulary Rays- A straight line used to represent a light wave. 2.Regular Reflection- A reflection that occurs when parallel rays of light hit a smooth surface and all reflect at the same angle. 3.Image- a copy of an object formed by refracted rays of light. 4.Diffuse Reflection- Reflection that occurs when a parallel rays of light hit an uneven surface and all reflect at different angles. 5.Plane Mirror- A flat mirror that produces an upright, virtual image the same size as the object. 6.Virtual Image- An upright image formed where rays of light appear to come from.

Vocabulary Concave Mirror- A mirror with a surface that curves inward. 8.Optical Axis- An imaginary line that divides a mirror in half. 9.Focal Point- The point at which light rays parallel to the optical axis meet, or appear to meet, after being reflected (or refracted) by a mirror or a lens. 10.Real Image- An upside-down image formed where rays of light meet. 11.Convex Mirror- A mirror with a surface that curves outward.

What is a scientific law? A statement that describes what a scientists expect to happen every time under a particular set of conditions. Scientific Theory? A well-tested explanation for a wide range of observations or experimental results. (NOT PROVEN)

Law of Reflection Law of Reflection states : The Angle of reflection equals the angle of incidence. outgoing or reflected Incoming/ incident ray Reflection involves two rays - an incoming or incident ray and an outgoing or reflected ray. In the figure 1(above), I’ve used a single line to illustrate a light ray reflected from the surface. The law of reflection requires that two rays are at identical angles but on opposite sides of the normal which is an imaginary line (dashed in Fig. 1) at right angles to the mirror located at the point where the rays meet. I’ve shown in Fig. 1, that the angles of incidence i and reflection i' are equal by joining the two angles with an equal sign.

What are the Kinds of Reflection? Pg. 322 To understand how light reflects: think of light waves as straight lines called rays, and a surface reflects light. Light obeys the law of reflection that states the angle of reflection equals the angle of incidence/incoming. The two ways in which a surface can reflect light ; 1.Regular reflection- (smooth surface) 2. diffuse reflection- (surface uneven)

What are the Kinds of Reflection? Pg. 323 The Two Ways in Which a Surface can Reflect Light Regular Reflection occurs when parallel rays of light hit a smooth surface. You see a clear image. An image is a copy of the object formed by reflected or refracted rays of light. Diffuse reflection occurs when parallel rays of light hit an uneven surface. You either don’t see an image or the image is not clear. Most objects reflect light diffusely.

Diffuse and Regular Reflection Which kind of reflection occurs on each surface? Reflection and Mirrors pg. 323

What Types of Images Do Mirrors Produce? Pg.324 A plane mirror is a flat sheet of glass that has a smooth, silver-colored coating on one side. Light strikes the mirror  the coating reflects the light The image you see in a plane mirror is a virtual image — an upright image that forms where light seems to come from. A plane mirror produces a virtual image that is: Upright Same size as the object The image, the left and right of the object are reversed.

What Types of Images Do Mirrors Produce? Pg.324 A concave mirror has a surface that curves inward, like the inside of a bowl. A concave mirror can reflect rays of light parallel to the optical axis so that they meet at a point. The optical axis is an imaginary line that divides a mirror in half. The point at which rays meet is the focal point. Optical Axis

Concave Mirror A concave mirror reflects rays of light parallel to the optical axis back through the focal point. (right hand index & thumb) Reflection and Mirrors

What Types of Images Do Mirrors Produce? Pg.325 Concave mirrors can produce two types of images: real virtual images. Real Image if: If the object is farther away from the mirror than the focal point. A real image forms when: light rays actually meet. A real image can be projected on a surface. Real images are upside down. A real image size may be: smaller, larger, or the same size as the object. Virtual Image if: If an object is between the mirror and the focal point Virtual Image size: the reflected rays form a virtual image that is larger than the object.

Real and Virtual Images The figures show how a concave mirror can produce both real and virtual images. Reflection and Mirrors

What Types of Images Do Mirrors Produce? Pg.325 A convex mirror has a surface that curves outward. When parallel rays of light are reflected by a convex mirror, the rays spread out but appear to come from a focal point behind the mirror. A convex mirror produces a virtual image The virtual image is always smaller than the object. (left hand index & thumb)

Convex Mirror Light rays parallel to the optical axis reflect as if they came from the focal point behind a convex mirror. Where do two reflected rays intersect behind the mirror? Reflection and Mirrors

Different Types of Images Formed by Mirrors Reflection and Mirrors

Compare and Contrast The Shape of a Convex and Concave Mirror Convex Mirror Concave Mirror

Resources Law of Reflection Tutorial Reflection of Light Java Waves activity Seismic waves travel through the Earth. There are two types - P waves and S waves. Find out more in this activity. ml Optics Workbench