2. Reflection ( 反射 )

3. incident rayreflected ray plane mirror angle of incidence angle of reflection normal Reflection of Light ( 光的反射 )

4. 3 Incident Rays ( 入射線 ) The light ray moving towards the mirror Reflected Rays ( 反射線 ) The light ray moving out of the mirror Normal ( 法線 ) The line perpendicular ( 垂直 ) to the mirror Angle of incidence ( 入射角 ) The angle between the incident ray and the normal. Angle of reflection ( 反射角 ) The angle between the reflected rays and the normal.

5. incident ray reflected ray Laws of reflection: The angle of reflection r equal to of incidence i. plane mirror i r 1.1. is the angle normal vertical plane Laws of reflection ( 反射定律 )  i =  r

6. Laws of reflection: The incident ray, the reflected ray and the normal all lie in the same plane. incident ray reflected ray normal plane mirror vertical plane 2.2.

7. 6 i = 0 r = 0 air mirror When the angle of incidence equals to zero (  i = 0), the angle of reflection is also zero (  r = 0).

8. 7

9. 8 40° 60° 30° 45°

10. 9 5.3 Experiment ( 實驗 ) 電源 光箱 量角器 平面鏡

11. 10 i /  030456075 r /  Conclusion ( 結論 ) The angle of incidence is ____________ the angle of reflection.

12. 11 i /  030456075 r /  030456075 Conclusion ( 結論 ) The angle of incidence is _equal to_ the angle of reflection.

13. Will the reflected rays remain parallel ( 平行 ) after reflection? Regular reflection ( 單向反射 )

14. same i same r  The reflected rays are therefore parallel. i i i r r r parallel incident rays parallel reflected rays plane mirror  Each light ray obeys the laws of reflection. For flat ( 平 ) and smooth ( 滑 ) surface,

15. plane mirror Regular reflection ( 單向反射 ) occurs at:

16. The following reflecting surfaces can form clear images due to regular reflection. a calm water surfacemetal surface

17. For rough ( 粗糙 ) surface, i1i1 i2i2 i3i3 r1r1 r2r2 r3r3 rough surface parallel incident rays reflected rays are not parallel Each light ray obeys the laws of reflection. different i different r Diffuse reflection ( 漫反射 )

18. Diffuse reflection occurs at a rough surface (e.g. a piece of paper). e.g. a piece of paper

19. Lateral inversion ( 橫向倒置 ) Mirror images are laterally inverted.

20. The laterally inverted words on an ambulance ( 救護車 ) the object image formed by the plane mirror

21. An image formed by a plane mirror is 1. same size as the object, ( 橫向倒置 ) 2. laterally inverted. ( 橫向倒置 ) 3. same distance

22. 21

23. 22

24. 23 Uses of plane mirrors ( 平面鏡的應用 ) rear-view mirrors ( 倒後鏡 )

25. 24 Explain why the Chinese characters 救護車 are printed in the special way as shown.

26. 25 So that the driver of the car in front of the ambulance can see the Chinese characters 救護車 without lateral inversion.

27. Periscope ( 潛望鏡 )  A periscope consists of two mirrors  The mirrors make an angle of 45  with the line joining them.

28. Periscopes are used in a double-deckers ( 雙層巴士 )

29. 28 Periscope ( 潛 望鏡 ) used in submarine ( 潛水艇 ).

30. 29 Plane mirrors used in interior design ( 室內設計 ).

31. 30 Plane mirror used by dentist ( 牙醫 ).

32. 31 In Figure 5.4, draw ONE light ray from the head of the object to the eye after reflection from the two mirrors.

33. 32

34. 33 Homework: Assignment Book 1. Chapter 5 Q.1 – Q.8 (p.7-9) 2. Deadline: