1. Program of Studies
investigate light beams and optical devices, and identify phenomena that provide evidence of the nature of light (e.g., evidence provided by viewing the passage of light through dusty air or cloudy water)
measure and predict angles of reflection
investigate, measure and describe the refraction of light through different materials (e.g., measure differences in light refraction through pure water, salt water and different oils)

2. Unit C: Light and Optical Systems
Reflection
Refraction
Total internal reflection
Telescopes

3. Light travels in straight lines only

4. Shadows How do we know? We have a clear shadow.
Shadows form because light does not go around corners, so we can “block” light rays with opaque materials

5. Light travels in straight lines
The closer the object is to the light source, the more light is blocked, and a larger shadow is formed.

6. Light Travels in Straight lines

7. Reflection + Refraction

8. Reflection vs. Refraction
Material
Shiny
Change in density
What happens?
Light bounces
Light bends
Technology
Mirrors
Lenses

9. Reflection

10. Reflection Incident ray <i: Reflected ray <r: Normal
Beam of light going towards the reflective surface
Reflected ray <r:
Beam of light coming off the reflective surface
Normal
An imaginary line that runs perpendicular (at 90o) to the reflective surface.
Angle of incidence <i :
Incoming ray of light (from source)
Angle of reflection <r :
Reflected ray

12. Reflection

13. The normal
The angle of incidence and angle of reflection are measured from the normal!

14. Reflection

15. Infinite reflection

18. Reflection

19. The Law of Reflection First discovered by… Euclid <i = <r
The angle of incidence
equals
The angle of reflection

20. The law of reflection

21. Total Internal Reflection

22. Total internal reflection
But how can you “pour” laser light into your hand?
Light will reach a critical angle, and then reflect rather than refract

23. Total internal reflection
This is the principle behind fibre optics

24. Lab
Do lab activity on reflection pg 195 science in action, full lab write up

25. Refraction
As light passes from one material to another material, it speeds up or slows down
This causes the beam of light to bend, making objects appear broken, or in another place

26. Refraction

27. Refraction Incident ray <i: Refracted ray <r: Normal
Beam of light going towards the refractive surface
Refracted ray <r:
Beam of light coming from the refractive surface
Normal
An imaginary line that runs perpendicular (at 90o) to the refractive surface.

28. Refraction

29. Refraction-densities
As light goes from an object that is more dense to less dense (ex. From water to air) light bends away from the normal
As light goes from an object that is less dense to more dense (ex. From air to water) light bends towards the normal

30. Refraction

31. Refractive Index (Density)
Material Refractive Index
Air
Water 1.33
Glycerin 1.47
Immersion Oil 1.515
Glass
Diamond 2.42

32. Did someone say diamond?

33. Refraction makes it sparkly

34. Refraction-prisms…..Newton

35. Refraction-lens in eye….Al

36. Reflection vs. Refraction

37. Telescopes

38. Light bends (refracts) through glass objective lenses
Types of Telescopes!
Three Basic Types
Refracting
Combination
Light bends (refracts) through glass objective lenses
Uses the best of both!
Reflecting
Mirrors reflect images to eyepiece. Focuses colors better: Newton’s Telescope

39. Do Lab Refraction pg 202