1. Geometrical Optics
14.2

2. Getting There Fast – Are you studying for the final yet??
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday 1 2 3
4 Complete Induction 5 6 AC 7 8
Quiz? 9 10 11
COMPLETE
AC EXPT 12
13 OPTICS
EM Waves
POLARIZATION 14
15 OPTICS
Quiz 16 17 18
EXAM #3
(No Optics) 19
20 OPTICS 21
22 OPTICS 23 24
25 (LAST LASS)
OPTICS 26 27 28 29
30 FINAL
HPA 119
9:00 AM

3. This week
This week we will cover some topics in geometrical optics. This will include mirrors and lenses. This is about all that we will be able to accomplish.
Only what we cover in class will be covered on the final examination.
There will be NO QUIZ this week.
The final exam will be on Saturday, April 30th in room HPA (Two Index Cards allowed)
Entire semesters work.
Joint exam with other Studio Class.
Watch for new WebAssign and probably one after that.

4. Next Week Monday Wednesday-Friday Saturday
Post Test (will be used for borderline cases)
Complete topics and possibly some problems
Wednesday-Friday
If there is coordinated interest, I might be able to come to campus and go over some problems. Need to find some common day/time to do this.
Saturday
Final Examination (2 index cards allowed).

5. About the final examination
Only topics discussed
In class,
On class PowerPoint lectures
Contained in the lab sheets,
Included in WebAssigns or
Assigned for reading
will be covered on the final exam.
That’s a lot of stuff!

6. NOTICE:
Bring ALL Lab Units from Magnetism Through Optics to class on Friday. One of them will be collected for grading.
STUDIO UNIT ???

7. Geometrical Optics
Yup … more angle stuff!

8. Geometrical Process
Object
Image
Lens or
Mirror

9. Where’s the image, where’s the object … who cares??? We do!
Questions about the image:
What kind of an image is it?
Real
Virtual
Where is the object, where is the image?
Behind the mirror
In front of the mirror
Where is the light coming from? Where is it going?
What is the size of the image? (magnification)
What is the orientation of the image?
Same as the object,
Inverted (upside down)
Reverse

10. What kind of optics: Mirror Lens Where is the light? Planar Concave
mirrors
Mirror
Planar
Concave
Convex
Lens
converging
diverging
Where is the light?
Have you seen the light yet?

11. Note The object is usually the source of light.
The image is where the light converges to replicate the object.
The image can be on either side of the “optical element”
The image can be real or virtual
The image can form an object for a second optical element.
Yes .. it can be confusing. We will attack this a point at a time. You have done some of this in the units so this is a review of sorts.

12. Signs – We mean (-) or (+)
The distance from the object to the lens/mirror is called the object distance.
It is positive if it is on the same side of the optical element as the incoming light. Otherwise it is negative
It is designated by s
The distance from the image to the lens/mirror is called the image distance.
It is positive if it is on the same side as the outgoing light
It is designated by s’. Otherwise it is negative.
Without this sign convention, these problems would be much more difficult. So pay attention to them!!

13. Consider looking in a plane mirror in your bathroom
Consider looking in a plane mirror in your bathroom. Your image distance is
Positive
Negative
This convention doesn’t apply to my bathroom mirror.

16. Paraxial Rays : Small Angle Approximation
theta
sin
tan
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
0.11
0.12
0.13
0.14
0.15
0.16
0.17
0.18
0.19
0.20
0.21
0.22
0.23
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0.25
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0.29
0.30
0.31

17. M I r o P l a n e

19. Curved Mirrors
For Student Misery Only!

20. Concave Mirror
con-CAVE

21. Sign Convention When the Center of Curvature
is on the same side of the
outgoing ray, R is positive.
Otherwise, if the center of
curvature is not on the same side
as the outgoing ray, R is negative.

22. Concave Mirror/Paraxial Approximation
The normal to the
surface passes
through C
Therefore
Consequently
MIRROR
EQUATION

23. For this structure The Radius R is positive and s’ is negative
The Radius R is negative and s’ is negative
R is positive and s’ is positive
R is negative and s’ is positive
Answer

24. When the Center of Curvature is on the same side of the
outgoing ray, R is positive.
the image distance is positive if it is on the same side as the outgoing light

25. This image is real, reversed virtual, not reversed real, not reversed
virtual, reversed

26. What about here? R, s, s’ (convex mirror)

27. Concept: Focal Length of a Mirror

28. Going Backwards

29. For a convex mirror, the Radius
Is positive
Is negative
The sign depends on the position of the image.
The sign depends on the current sign of the zodiac.

30. R When the Center of Curvature is on the same side of the
outgoing ray, R is positive.
Otherwise, if the center of
curvature is not on the same side
as the outgoing ray, R is negative.

31. Image Formation – Ray Diagram‘ ‘
y’<0
(from the diagram) so image is inverted.

32. Continue the current Unit

33. Examples to review

34. A concave spherical mirror has a radius of 10 cm
A concave spherical mirror has a radius of 10 cm. Calculate the location and size of an 8mm object a distance 15 cm from the mirror.
10 cm cm
Normal to mirror
and bounces back
along incoming
path.

35. A concave spherical mirror has a radius of 10 cm
A concave spherical mirror has a radius of 10 cm. Calculate the location and size of an 8mm object a distance 10 cm from the mirror.
10 cm cm

36. A concave spherical mirror has a radius of 10 cm
A concave spherical mirror has a radius of 10 cm. Calculate the location and size of an 8mm object a distance 2.5 cm from the mirror.
10 cm cm
virtual
image
eye

37. The Concave Mirror The Equations are the same as the convex mirror
but the Radius of the mirror is negative

38. More Convex Mirror

39. Graphical Methods are very useful to check your work.