1. Do Now:
What are the photosensitive cells that respond to black, white and shades of grey?
What are the photosensitive cells that respond to color?
What is the condition where the eyeball is too long and the lens forms images in front of the retina?
What is the condition where the eyeball is too short where the lens forms images behind the retina?

2. Learning Intentions: Students will be able to
Differentiate between concave and convex lenses
Describe how light is reflected and refracted

3. Four ways light is affected by matter

4. Four ways light is affected by matter
All four interactions almost always happen together.
A glass window is mostly transparent but also absorbs about 10% of light.
The glass scatters some light (translucency) and reflects some light.
Can you tell which colors are reflected and which are absorbed?

5. Optics Optics is the study of how light behaves
Three useful optical devices are:
Lenses
Mirrors
Prisms

6. Lenses A lens is a polished, transparent disc, usually made of glass
Bends light

7. Converging and Diverging Lenses
Converging lens: bends light so it comes together
Diverging lens: bends light so it spreads apart

8. Optical Devices A magnifying glass is a converging lens.
In survival situations, it can be used to make a hot spot.

9. Reflection Reflection occurs when light bounces off a surface
Mirror – reflects light and creates an inverted image

10. Reflection There are two types of reflection; not all form images.
A ray of light that strikes a shiny surface (like a mirror) creates a single reflected ray.
This type of reflection is called specular reflection.

11. Reflection
A surface that is dull, (or uneven) creates diffuse reflection.
When you look at a diffuse reflecting surface you see the surface itself.

12. Refraction
Refraction occurs when light bends while crossing through materials
A prism refracts light rays distorting an image

13. Refraction
Materials with a higher index of refraction bend light by a large angle.
The index of refraction for air is about 1.00.
Water has an index of refraction of 1.33.

14. Refraction
Vegetable oil and glass have almost the same index of refraction.
If you put a glass rod into a glass cup containing vegetable oil, the rod disappears because light is NOT refracted!

15. What do you see?

16. What do you see at first an old lady or a young woman?

17. What do you see?

18. How Many Prongs Are on This Fork?

19. What do you see?

20. There Is Not a Triangle Here.

21. This Is a Dancing Elephant. How Many Feet and Legs Does It Have?

23. What Does This Say? Now Read It Again!

24. A Man With Ivy Leaves Around Him, but Do You See a Couple Kissing?

25. The nose is actually the girl’s face
The eyes of the old man are the hair for the boy and girl
The beard is the dress for the girl on the right and the clothes for
The boy on the left.

27. Independent Work:
Take the rest of the class period to review for tomorrow’s quiz
Review questions cover all the material on the quiz
If you have questions – now is the day to ask 