CHAPTER 9 LESSON 2Reflection and mirrors

Sunshine state standards

SC.7.P.10.2 Observe and explain that light can be

reflected, refracted, and/or absorbed. La.7.2.2.3

The student will organize information to show understanding (e.g. Representing main ideas through charting)

Page 324

Read My planet Diary on page 322

What are some of the things that you may see underwater?

How does the periscope work?

What are the different types of reflections?

REGULAR REFLECTION

Diffuse Reflection

REGULAR REFLECTION

Diffuse Reflection

Regular Reflection Definition:

A reflection occurs when parallel rays of light hit a smooth surface.

Rays: Visible light waves that are represented as straight lines.

All rays reflect at the same angle because of the smooth surface.

Regular Reflections

Image definition:An image is a copy of the object formed by reflected or refracted rays of light

Diffuse Reflection

Definition: A diffuse reflection occurs when parallel rays

of light hit an uneven surface. Each light ray obeys the law of reflection

but because the surface is uneven the rays reflect at different a angles which makes the image unclean or distorted.

Most objects have diffuse reflections or images even if they appear flat like paper or blades of grass.

Diffuse reflections

Complete figure 1 on page 323

Label the kind of reflection that occurs on each surface.

Plane Mirror Definition:

A flat sheet of glass that had a smooth, silver-colored coating on one side.

The coating is smooth and regular and a virtual image is formed.

Virtual images Definition: An image that forms where light

seems to come from. Images that seem real but do not really exist,

such things “inside” the mirror. Virtual images produced by plane mirrors

are upright and the same size as an object.

Plane mirror virtual images

Figure 2 page 324

1. Explain the similarities and differences of the ballet dancer in the picture.

2. Is the raised hand in the mirror an the dancers right or left hand?

Concave Mirrors

Definition: A mirror with a surface that curves inward like the

inside of a bowl. Optical Axis:

An imaginary line that divides a mirror in half (like the equator on the earth)

Concave mirrors create a focal point which is the point at which the rays that are parallel to the optical axis meet.

Concave mirrors produce Virtual and real images

Real images: Definition: forms when light rays actually meet. Real images are formed past the focal point and are upside

down. Real images can be smaller, bigger, or the same size as the

actual object. If the real image is produced past the object then the

real image will appear larger then the actual object. If the image is produced before the object then the

real image will appear smaller then the actual object. Virtual images created by concave mirrors are

upright and appear larger then the actual object

Complete Figure 3 on page 325

1. The image is real, upside down, and smaller than the object

2. The image is real, upside down, and larger than the object

3. The image is virtual, right-side up, and larger than the object.

Convex Mirrors

Definition: A mirror with a surface that curves outward

The reflected rays spread out after they reflect off the mirror so the focal point actually appears to form “inside” the mirror.

This causes the image formed by convex mirrors to be a virtual one and make the object appear smaller then the actual object.

Complete figure 4 on page 326

Pictures and video clips from discovery education