1. Mirrors

2. There are 3 types of mirrors
A. Plane mirrors
B. Concave mirrors
C. Convex mirrors

3. Image Types:
Real or Virtual
Upright or Inverted
Reduced or Enlarged

4. Real or Virtual Real: image projected on a screen
Virtual: image can only be seen inside the mirror

5. Upright or Inverted Inverted: Image is oriented the opposite direction
Upright: Image is oriented the same direction as the object

6. Reduced or Enlarged Enlarged: image is larger in size
Reduced: image is smaller in size

7. Law of Reflection
All mirrors obey the law of reflection(no matter the shape)
The NORMAL line is always perpendicular
to the mirror.

8. Plane Mirrors Images are: A. Behind the mirror (VIRTUAL) B. Same size
C. Right side up
Only the right and left of the image is changed.

9. A. Concave B. Convex Curved Mirrors
They can be considered cut outs of a spherical mirror
Curved mirrors can be either . . .
A. Concave
B. Convex

10. Concave Mirrors

11. Concave Mirror Terminology
A concave mirror can be considered to be part of a larger, spherical mirror.
The principal axis is the line that runs through the center of the mirror
The center of curvature is the very center of the mirror, denoted with the letter C.
The point where the principal axis meets the mirror surface is called the vertex.

12. On a diagram, the focal point is represented with the letter F
The focal point is the midpoint or halfway between the vertex and the center of curvature
The focal point is the location where reflected light rays converge (come together)
On a diagram, the focal point is represented with the letter F
The focal length (f) is the measured distance from the mirror to the focal point.

13. Images of Concave Mirrors
Images formed by concave mirrors be either virtual or real
Virtual images form behind the mirror (light rays appear to intersect)
Real images form in front of the mirror
Real images can be collected on a screen
For real images, reflected light rays actually converge, or come together, and produce an inverted image
Real images form in front of the mirror!

14. Terminology C: Center of Curvature- geometric center
Normal line (axis)
Object
C: Center of Curvature- geometric center
F: Focal Point (1/2 of C)

15. Image formation- Ray Diagrams
Two rules for identifying images of concave mirrors:
Any incident ray that comes in parallel to the principal axis will reflect through the focal point.
Any incident ray that travels through the focal point will reflect parallel to the principal axis.

16. Ray One:
Draw a parallel line from the top of the object to the mirror.
This line should bounce off the mirror and through the focal point.

17. Ray Two:
Draw a line from the top of the object through the focal point to the mirror.
This line should bounce off the mirror and go parallel to the axis.

18. Final step: Draw the image where the 2 lines converge…
Make sure the bottom of the image is on the principle axis, and the top of the image is at the convergence point.

20. Ray Three:
Draw a straight line from the top of the object and through the Center of curvature.

21. Image Characteristics: LOST
L: What is the image location?
O: What is the image orientation? Is it upright or inverted?
S: What is the image size? Is it larger, smaller, or the same size as the object?
T: What is the image type? Is it real or virtual?

22. No image?
If it appears that no image will form in front of the mirror, extend the REFLECTED rays behind the mirror
If the REFLECTED rays meet, a VIRTUAL image forms

23. Distant Objects: Beyond C
The image of an object located beyond C will form:
Between C and F
Be reduced

24. Objects At C:
The Image will be:
Real
Same location as object
Inverted
Same size

25. Objects Between C and f:
The Image will be:
Real, Inverted, Enlarged
Image is located beyond C

26. Objects Inside f:
The Image will be:
1.Virtual, upright, enlarged

27. Summary Plane Mirrors Concave Mirrors Location
Form images behind the mirror
Form in two locations, either behind the mirror or in front of the mirror
Orientation
Images are always upright
Virtual images are upright
Real images are inverted
Size
Images are same size
Images can be same size, reduced, or enlarged
Type
Form VIRTUAL images only
Can form VIRTUAL and REAL images

28. Location of Image
do = distance of object
di = distance of image
f = focal length(distance between mirror and focal point)

29. Magnification of Image
hi = height of image
ho = height of object

30. Example Problem
An object 2.0 cm high is 30.0 cm from a concave mirror. The radius of curvature of the mirror is 20.0 cm.
A) What is the location of the image?
B) What is the size of the image?

31. Review Real images are inverted and form in front of the mirror.
Virtual images are upright and form behind the mirror.
Plane mirrors diverge light rays and form only virtual images.
Concave mirrors converge light rays and form both real and virtual images.

32. Convex Mirrors Diverge Rays of Light “Curved out”

33. Convex Images
All convex mirrors form
virtual images
Upright
Smaller

34. Ray Tracing for Convex Mirrors
Very similar to ray tracing for concave mirrors
The focal point and center of curvature are BEHIND the mirror

35. Ray One:
Draw a parallel line from the top of the object to the mirror. Stop at the mirror!
An imaginary line should be drawn from this point to the focal point.
The reflected ray is extended back from the mirror along the path of the imaginary line

36. Ray Two:
Draw a line from the top of the object toward the focal point on the other side of the mirror, but stop at the mirror.
Draw a reflected ray parallel to the principle axis
Extend the reflected ray behind the mirror

37. Ray Three:
Draw a straight line from the top of the object and to the center of curvature.

38. Final step: Draw the image where the 3 lines converge…
Images are reduced, upright, virtual

39. Reviewing the three rays:
Parallel, then through f.
Through f, then parallel.
Straight line through top of object and C.