1. Phy2005 Applied Physics II Spring 2017 Announcements:
Exam and updated HITT grades posted on Canvas

2. For a small object, f = R/2 (spherical mirror)
Last time:
Mirror Equation
1/p + 1/q = 1/f
For a small object, f = R/2 (spherical mirror)
1/p + 1/q = 2/R
Alert!!
Be careful with the sign!!
Negative means that it is behind the mirror!!
p defined to be positive
negative q means virtual image
How about f?

3. Focal point inside the mirror
Last time
For a concave mirror: f > 0
Convex mirror:
Focal point inside the mirror
f < 0
1/p + 1/q = 1/f < 0 : q should be negative.
Magnification, M = -q/p
Negative M means that the image is upside-down.
For real images, q > 0 and M < 0 (upside-down).

4. Refraction and Lenses
The pencil is not bent at the air-water boundary.
It is caused by non-trivial passage of light rays.

5. Who has the better chance to save this drowning guy?
Pam Anderson, whose path
takes the shortest time Li
David Hasselhoff
Jeremy Jackson
Pamela Anderson
Light travels the path that takes the
shortest time between two points

6. All three beams (incident, reflected, and refracted) are in one plane.
v: speed of light in a medium < c
n = c/v :index of refraction
n > 1
Snell’s Law
All three beams (incident, reflected, and refracted) are in one plane. q1 q2
air
glass
v1 = c/n1, v2 = c/n2
n1sinq1 = n2sinq2

7. material n = c/v n depends on l. Index of Refraction vacuum 1.00 air
for l = 589 nm
vacuum
1.00
air
water
1.33
ice
1.31
typical glass
1.52
polycarbonate
1.59
diamond
2.42
n depends on l.
Dispersion

8. Apparent position and actual
position are different due
to refraction.

9. Total internal reflection when q2 = 90
from glass into air
n1 (> n2) q1
n1sin(q1) = n2sin(q2)
Total internal reflection when q2 = 90
sin(qc) = n2/n1
< 1
qc: critical angle

10. Example: fisheye view air/water interface qfisheye = 2qc
qfisheye = angular
range fish can
see
qc = sin-1(1/1.33)
= 49

11. Optical Fiber
Total internal reflection!
ncore nclad
>

12. Q. What is the critical angle for a glass to air surface if the
index of refraction for glass is 1.5?
sinqc = na/ng
= 1.0/1.5
= 0.667
qc = 42

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14. Q2 A fish swims below the surface of the water
Q2 A fish swims below the surface of the water. Suppose an observer is looking at the fish from the side. The observer sees
the fish at a greater depth than it really is.
the fish at its actual depth.
the fish at a smaller depth than it really is.
no fish due to total internal reflection.

15. Q3 A fish swims below the surface of the water
Q3 A fish swims below the surface of the water. Suppose an observer is looking at the fish straight above the fish. The observer sees
the fish at a greater depth than it really is.
the fish at its actual depth.
the fish at a smaller depth than it really is.
no fish due to total internal reflection.

17. Clicker Quiz Time Log in your remote! ACADEMIC HONESTY
Each student is expected to hold himself/herself to a high standard of academic honesty. Under the UF academic honesty policy. Violations of this policy will be dealt with severely. There will be no warnings or exceptions.
Log in your remote!

18. There are three layers of different media as shown in the figure.
A beam of light bends as shown in the figure when it passes through
the media. What can we say about the relative index of refraction
of these materials?
The media I-II-III have indices of
refraction that get smaller
2) One of the media is a vacuum
3) One of the media is glass
4) The media I-II-III have indices of
refraction that get bigger
5) Two of the media are the same I II
III

19. nIIsinqII = nIIIsinqIII qII > qI  nI > nII
nIsinqI = nIIsinqII
nIIsinqII = nIIIsinqIII
qII > qI  nI > nII
qIII > qII  nII > nIII
nI > nII > nIII I II
III

20. “Dispersion” of Index of Refraction for Glass
wavelength (nm) n
361 (near UV)
1.539
434 (dark blue)
1.528
486 (green)
1.523
589 (yellow)
1.517
656 (red)
1.514
768 (dark red)
1.511
1200 (IR)
1.505
2000 (far IR)
1.497

21. Air
Water

23. In glass
n (red) ≈ 1.51
n (purple) ≈ 1.53

26. What is the angle between the red (4.6x1014 Hz)
and blue (6.3x1014 Hz) rays emerging from a 30o
prism as shown?
n, quartz
1.48
1.47
30o
white
1.46 q
1.45
300
500
700
l(nm)
sin q = n sin 30o = n/2
Ans: Radian = 0.23o