1. Refraction
n =1
n =1.3
Bending of light rays at boundaries with different indices of refraction (n)
n =1.5
n =2.4

2. Snell’s law of refraction
Light in the highest index (slowest) material has the smallest angle vs the “normal” direction.
faster
slower
(water, glass)
Illustration

3. Apparent depth is less than true depth

4. P1. A laser beam enters and exits a piece of flat glass
P1. A laser beam enters and exits a piece of flat glass. For the beam shown below, where could it exit? _______ P2. Compared to the direction of the original beam in air, when it exits, the beam direction will be __________ a) farther from the normal b) the same c) closer to the normal

5. Diffuse reflection or “scattering”
Almost everything scatters light in all directions: paper, paint, sidewalks, leaves, cloth.

6. Specular reflection (mirror-like)
Smooth surfaces (bumps smaller than a wavelength of light) are “mirror-like” (you can see images in them)

7. Many surfaces are somewhere between these extremes

8. Law of specular reflection
Photons bounce like balls off a smooth floor: vertical momentum is reversed, horizontal momentum is conserved.

9. Imaging in planar mirrors
A flat mirror creates an image of the world, with each image point “appearing” behind the mirror the same distance the object point is from the mirror
Why is one baby bigger than the other in the photo?

10. Rays from the lid go in all directions, but only the narrow bundle shown will get to the eye

11. The image location is where the object appears to be, looking into the mirror.
It’s on the other side of the mirror, the same distance from the mirror as the object. To see this image clearly your eyes would have to focus to the image location beyond the mirror.

12. Nonplanar mirrors

13. How big does a mirror need to be to see all of you?
Think of the mirror size as a “window” into a copied world.

14. B A C E D
P3. The red dot is above the mirror. Where is the image of the red dot?

15. P4. How many of the people can see the red dot in the mirror?
A.1 B.2 or 3 C.4 or 5 D. 6

16. Medical story about a mirror

17. Focal lengths of curved mirrors
Concave
Convex

18. Imaging equation Magnification
This image is inverted, enlarged (|m|>1), and real (you could put a screen there and see it…the light rays meet at the image)

19. Imaging equation
This image appears closer to us (using depth perception) than the original key. And using a ruler next to it, it would be longer.

21. This image is upright, enlarged, and virtual (di is -), the rays only appear to come from the image point, but never converged there)
Mirror demo in ESC lobby

22. To see this image clearly your eyes would have to focus several meters behind the mirror. If you put a tape measure at that point, I would appear to be several meters tall.
Mirror demo in ESC lobby

23. Imaging with convex mirrors
"The picture shows a spherical mirror, resting on [my] left hand…  Such a globe reflection collects almost one's whole surroundings in one disk- shaped image.  the whole room, four walls, the floor, and the ceiling, everything, albeit distorted, is compressed into that one small circle.  Your own head, or more exactly the point between your eyes, is the absolute center.  No matter how you turn or twist yourself, you can't get out of that central point.  You are immovably the focus, the unshakable core, of your world."  - M. C. Escher

24. Imaging with convex mirrors
For any object distance, the image is ______, _______, and _______. upright--or--inverted real--or--virtual magnified--or--reduced

25. P5. The strongest mirror (shortest f) is P6
P5. The strongest mirror (shortest f) is P6. An object is a distance of 60 cm from a convex mirror with focal length 20 cm. Where is the image from the mirror? Careful with sign of f. A. 10 cm B. 15 cm C. 20 cm D. 25 cm E. 30 cm

26. In this demo, the image appears (inverted) just above the object, so di = do (m = -1). What is that distance between the bulb and the mirror? A. f/2 B. f C. 2f D. 4f