1. Optics In this unit: Properties of light Reflection Lenses
And applications of optics
Refraction

2. Recap of Light
Light travels in straight lines – until bent when passing through a different substance - REFRACTION
Light travels much faster than sound
Light is either reflected or absorbed
We see things because they reflect light into our eyes
Objects can be Luminous or non-luminous

3. Recap of Light
Light Form of energy – specifically the electron movement from one orbital shell to another Visible Light Spectrum of energy wavelengths that the human eye can detect Light Sources (11.1, 11.2) Fluorescence, incandescent, bioluminescence, chemiluminescence, etc

4. Reflection Terminology
Reflection from a mirror:
Normal
Incident ray
Reflected ray
Angle of incidence
Angle of reflection
Mirror

5. Clear vs. Diffuse Reflection
Specular Reflection: Smooth, shiny surfaces have a clear reflection:
Rough, dull surfaces have a diffuse reflection.
Diffuse reflection is when light is scattered in different directions

6. Clear vs. Diffuse Reflection

7. converge: come together
We see images when
light rays
converge in our eyes.
converge: come together

8. Yesterday you learned how to draw images in a Plane Mirror
Draw line & measure
Repeat lines behind mirror
2cm
2cm
object
3.5cm
3.5cm
mirror

9. Characteristics of images in plane mirrors
The image in a plane mirror is always
Same size as the object
Upright, inverted laterally
Behind the mirror and
Virtual (an image formed in a location that the light does not actually reach)

10. Forming Images with a Plane Mirror
Light reflected from the flower and vase hits the mirror. Obeying the law of reflection, it enters the eye. The eye interprets the ray as having had a straight-line path, and sees the image behind the mirror.

11. Plane Mirrors (flat mirrors)
How do we see images in mirrors?

12. Plane Mirrors (flat mirrors)
object
image
How do we see images in mirrors?
Light reflected off the mirror converges to form an image in the eye.

13. Plane Mirrors (flat mirrors)
object
image
How do we see images in mirrors?
Light reflected off the mirror converges to form an image in the eye.
The eye perceives light rays as if they came through the mirror.
Imaginary light rays extended behind mirrors are called sight lines.

14. Steps for drawing Plane Mirror Ray Diagrams:
1. A ray that strikes perpendicular to the mirror surface, reflects perpendicular to the mirror. The reflected ray is extended beyond the mirror. 2. A ray that strikes the mirror at any angle reflects so the angle of incidence equals the angle of reflection. The reflected ray is extended beyond the mirror.

15. Using Ray diagrams
draw a ray diagram to show how Suzie will be able to see the image of the green object arrow in the diagram (this is a proof)

16. The four steps of the process
Draw the image of the object.
Use the principle that the object distance is equal to the image distance to determine the exact location of the object

17. 2. Pick one extreme on the image of the object and draw the reflected ray that will travel to the eye as it sights at this point.

18. 3.Draw the incident ray for light traveling from the corresponding extreme on the object to the mirror.

19. 4. Repeat steps 2 and 3 for all other extremities on the object.

20. Examples

22. Uses of Ray Diagrams
Ray diagrams are useful tools for determining and explaining what objects might be viewed from certain locations
For example, suppose that six students - Al, Bo, Cy, Di, Ed, and Fred sit in front of a plane mirror and attempt to see each other in the mirror

23. Yesterday’s Handout – Activity 1
Whom can Al see? Whom can Bo see? Whom can Cy see? Whom can Di see? Whom can Ed see? And whom can Fred see?

24. First step is to draw out where you know the images will be
First step is to draw out where you know the images will be. Then use ray diagrams to figure out who each person can see.

25. Activity 2
P489 TRY THIS “producing images” Text work: P493 #1,3,7,9

26. Activity 3 – New handout
A periscope: Utilizes mirrors to help view around objects – such as tank commanders to inspect their situation without leaving the safety of the tank or in a submarine
A periscope

27. Using Plane Mirrors
The kaleidoscope – fun uses of plane mirrors

28. First Al is isolated from the rest of the students and lines of sight are drawn to see who Al can see
Al’s lines of sight are limited by the edges of the mirror. Only Ed and Fred are within these sight lines.

29. Bo can see Di, Ed, and Fred Cy can see Cy, Di, Ed, and Fred Di can see Cy, Di, Ed, and Fred Ed can see Bo, Cy, Di, and Eve Fred can see Al, Bo, Cy, and Di