1. Step 1
Identify the top and the bottom of the object (label these “A” and “B”)

2. for reflections in a plane mirror
Ray Diagrams
for reflections in a plane mirror

3. Step 2
Draw a line from point A that is perpendicular to the mirror

4. Step 3 Draw an incident ray (starting at point A)
Draw a “normal” where the incident ray hits the mirror
Use a protractor to draw a reflecting ray
(Remember that i = r )

5. Step 4
Extend line A to point Ai (equidistant from point A on the other side of the mirror)
Connect point Ai to your reflection ray

6. Step 5
Repeat steps 2-4 for Point B

7. Try it!

8. Reflection Characteristics
Attitude (a.k.a. Orientation)
Type
Inverted
Upright
Size
Real
Virtual
Laterally Inverted
Location
Same
Enlarged
Same side
At a particular point (i.e. at C, f<di<2f, etc.)
Opposite side
Reduced

9. Type
Real - image appears in front of the mirror (could be projected onto a screen)
Virtual - image appears behind the mirror

10. Size a) Enlarged - image is larger than the object
b) Reduced - image is smaller than the object
c) Same - image is the same size as the object a) b) c)

11. Attitude MIRROR MIRROR MIRROR MIRROR
a) Upright - image is right-side up
b) Inverted - image is upside-down
c) Laterally Inverted - image is flipped horizontally a)
MIRROR b)
MIRROR
MIRROR c)
MIRROR

12. Location Image is located on the same side of the mirror
Image is located on the opposite side of the mirror
Image can also be located at a specific point (e.g. at centre of curvature, f<di<2f, etc.)
Note: image location will always be di=do for plane mirrors

13. Curved Mirrors

14. Curved Mirrors
Concave
Convex
“converging” mirror
“diverging” mirror

15. Concave Mirrors

16. Concave Mirrors

17. Terminology Focal Point (F) - where the light rays meet
Vertex - the middle point of a curved mirror
Focal Length (f) - the distance from the focal point to the vertex
vertex f
principal axis

18. Concave Mirror Ray Diagrams
Ray 1 - travels parallel to the principal axis and reflects through the focal point (F)

19. Concave Mirror Ray Diagrams
Ray 2 - travels through the focal point and reflects parallel to the principal axis

20. Concave Mirror Ray Diagrams
The point where the two reflected rays converge will be the location of the image

21. Concave Mirror Ray Diagrams
A third ray (shown in red) should be drawn as a “check”
This can only be used if the Centre of Curvature (“C”) is present in the diagram – which is usually 2X focal length.

22. You try!
Turn your notes over
There are 5 “cases”

23. Concave Mirror Reflections
5 Cases
Object is greater than 2 focal lengths from the mirror (do>2f) – note: 2f = C
Object is at 2 focal lengths/Centre of Curvature (2f/C)
Object is between 1 and 2 focal lengths from the mirror (f<do<2f)
Object is at the focal point (do=f)
Object is between the mirror and the focal point (V<do<f)

24. Case 1: Object beyond 2f/C
Type
Size
Attitude
Real
Reduced
Inverted

25. Case 2: Object at 2f/C
Type
Size
Attitude
Real
Same
Inverted

26. Case 3: Object between 2f and F
Type
Size
Attitude
Real
Enlarged
Inverted

27. Case 4: Object at F
Type
Size
Attitude
No Image Formed!

28. Case 5: Object between F and V
Type
Size
Attitude
Virtual
Enlarged
Upright

29. “Drawing Ray Diagrams for Concave and Convex Mirrors”
Handout p.429
“Drawing Ray Diagrams for Concave and Convex Mirrors”