1. Curved Mirrors and Ray Diagrams SNC2D

2. Concave Mirrors A concave mirror is a curved mirror with the reflecting surface on the inside of the curve. The point C is the centre of curvature and the distance between C and the vertex A is the radius of curvature, R.

3. Concave Mirrors Halfway between C and A is F, the focal point or principal focus. The focal length, f = R/2.

4. The Focal Point The focal point is the point at which rays incident parallel to the principal axis will meet after reflection.

5. The Focal Point The focal point is the point at which rays incident parallel to the principal axis will meet after reflection. (Recall the Law of Reflection. In this case, the normal to the mirror is the radius.)

6. Image Formation Where and how is an image formed?

7. Image Formation Where and how is an image formed?

8. Image Formation Where and how is an image formed?

9. 2 Rules of Reflection To locate an image, we will use the 2 rules: A ray travelling parallel to the principal axis will reflect through the focal point. A ray travelling through the focal point will reflect parallel to the principal axis.

10. Ray Diagrams: Step 1 From the top of the object, draw two rays towards the mirror, one parallel to the axis and one through the focal point

11. Ray Diagrams: Step 2 Reflect these rays according to the rules of reflection.

12. Ray Diagrams: Step 3 Mark the image of the top of the object at the intersection of the reflected rays.

13. Ray Diagrams: Step 4 The bottom of the image forms on the principal axis. Draw your complete image.

14. Image Characteristics Note that the image of an object beyond the centre of curvature of the mirror is: S: A: L: T:

15. Image Characteristics Note that the image of an object beyond the centre of curvature of the mirror is: S: Smaller A: L: T:

16. Image Characteristics Note that the image of an object beyond the centre of curvature of the mirror is: S: Smaller A: Inverted L: T:

17. Image Characteristics Note that the image of an object beyond the centre of curvature of the mirror is: S: Smaller A: Inverted L: Between F and C T:

18. Image Characteristics Note that the image of an object beyond the centre of curvature of the mirror is: S: Smaller A: Inverted L: Between F and C T: Real

19. Image Characteristics The characteristics of the image formed by the mirror will change with the location of the object. Ref: Practice Sheet: “Concave Mirrors and Ray Diagrams”

20. Concave Mirrors: Answers The image formed by an object beyond C is S: smaller A: inverted L: between F and C T: real

21. Concave Mirrors: Answers The image formed by an object at C is S: the same size A: inverted L: at C T: real

22. Concave Mirrors: Answers The image formed by an object between C and F is S: larger A: inverted L: beyond C T: real

23. Concave Mirrors: Answers There is no image formed by an object at F:

24. Concave Mirrors: Answers The image formed by an object between F and the mirror is S: larger A: upright L: behind the mirror T: virtual

25. Concave Mirrors: Answers The image formed by an object between F and the mirror is S: larger A: upright L: behind the mirror T: virtual

26. Convex Mirrors A convex mirror is a curved mirror with the reflecting surface on the outside of the curve. The centre of curvature and the focal point will be on the far side of the mirror. The focal length will be negative.

27. Convex Mirrors are Diverging Light rays reflecting from a convex mirror will diverge, i.e. never intersect. Any image formed is therefore always virtual.

28. Revised Rules of Reflection A ray travelling parallel to the principal axis will reflect such that the extension of the reflected ray will pass through the focal point. A ray travelling towards the mirror such that its extension will pass through the focal point will reflect parallel to the principal axis.

29. Ray Diagrams Again Step 1:

30. Ray Diagrams Again Step 2:

31. Ray Diagrams Again Step 3:

32. Ray Diagrams Again Step 4:

33. Ray Diagrams Again Step 4: The image is (S) smaller, (A) upright, (L) behind the mirror, and (T) virtual.

34. More Practice p. 427 #1 – 5 and p. 433 #15