The document defines key terms related to the reflection of light such as normal, angle of incidence, and angle of reflection. It states that the angle of incidence is equal to the angle of reflection and uses this principle in calculations and measurements. Examples are provided to demonstrate calculating angles of incidence and reflection from diagrams of light rays reflecting off plane mirrors.

1. REFLECTION OF LIGHT REFLECTION OF LIGHT

7. Reflection of light The abrupt change in the direction of propagation of light rays that strike the boundary between different medium.

8. Normal : plane  normal  normal center An imaginary line perpendicular to a surface where the reflection occurs.

9. Reflection of Light(1) i r Incident ray normal plane mirror The ray striking the surface (incoming ray) The ray reflected from the surface (outgoing ray) Reflected ray

10. Reflection of Light(2) The angle between incident ray and normal The angle between reflected ray and normal  i = angle of incidence  r = angle of reflection  i  r i r Incident ray normal plane mirror Reflected ray

12. The diagram shows a ray of light being reflected by a plane mirror MN. Which one of the following statements is completely correct ? A LP is the incident ray, PR is the reflected ray and x is the angle of reflection. B LP is the reflected ray, x is the angle of incidence and y is the angle of reflection. C LP is the incident ray, x is the angle of incidence and y is the angle of reflection. D PQ is the normal, x = y, and PR is the incident ray. C Example 1

13. Reflection by the plane mirror i r Plane mirror Note: Normal always perpendicular to the mirror i r Incident ray normal plane mirror Reflected ray  i = angle of incidence  r = angle of reflection  i  r

14. The diagram shows a ray of light reflected in a plane mirror. What is the angle of reflection? Example 2 Angle incidence = 90 0 - 40 0 = 50 0 Angle of reflection = Angle of incidence = 50 0

16. The diagram shows a ray of light striking a plane mirror. What is the angle of incidence if the total angle between the incident ray and reflected ray is 70  ? Example 4 Angle of incidence = Angle of reflection = 70 0 / 2 = 35 0

17. Example 5 In the figure below, ray AB will be reflected twice. Find the angle of reflection in the second reflection. Copy the figure and complete the path of the ray. angle r 1 = 30 0 ; angle r 2 = angle i 2 = 90 0 - 30 0 = 60 0  30 0 r 1 i 2 r 2  30 0 A B

18. MIRROR IMAGE(1) BIKE BOOK BOX CHOKE DECIDE CHICK

19. MIRROR IMAGE(1) BIKE BOOK BOX CHOKE DECIDE CHICK

20. MIRROR IMAGE(2) SPEED POLES BED LIGHT POWER CHECK

21. MIRROR IMAGE(2) SPEED POLES BED LIGHT POWER CHECK

25. A person stands 2.0 m in front of the mirror as shown. How far from the person is her image? Example Image is 4.0 m from the person.

26. The diagram shows two divergent rays of light from an object O being reflected from a plane mirror. At which position will the image be formed? Example B

27. i r Note: i = r object image normal eye object image mirror mirror Ray diagram showing the formation of an image

28. Image formed by the plane mirror

29. Plane mirror Regular reflection Black surface Absorption Irregular surface Diffuse reflection Glass block Transmission Glass Various cases of rays:

32. mirror mirror Periscope: Periscopes are used in submarines so that people below the water surface can see what is happening above. (Type 1)

33. prism prism Periscopes are used in submarines so that people below the water surface can see what is happening above. Periscope: (Type 2)

35. GCE O-Level Past Examination Paper Science (Physics)

36. November 1989 8 . Which of the following correctly describes the image formed in a plane mirror when compared to the object? A virtual smaller B virtual same size C virtual larger D real same size B

37. Nov 1990 6. An object ‘O’ is placed in front of a plane mirror. A viewer looks into the mirror as shown in the diagram. In which position is the image of O formed? B

38. Nov 1991 10. The diagram shows a ray of light being reflected by a plane mirror MN. Which one of the following statements is completely correct ? A LP is the incident ray, PR is the reflected ray and x is the angle of reflection. B LP is the reflected ray, x is the angle of incidence and y is the angle of reflection. C LP is the incident ray, x is the angle of incidence and y is the angle of reflection. D PQ is the normal, x = y, and PR is the incident ray. C

39. 4. The diagram below shows the position I of the image formed by a plane mirror of an object O. (a) Continue the two rays drawn leaving O to show how they would be reflected at the mirror. [2] GCE ‘O’ LEVEL Nov 1995 I O

40. 4.(b) I is a virtual image. Explain the meaning of this. [2] (Cont. …) Q. 4 Nov 1995 Since the image, I, is produced by the reflection of light and cannot project on a screen, there- fore it is a virtual image.