# – Waves, Lecture 8 PHY138 Today’s overview: Real Laser

```PHY138 – Waves, Lecture 8
Today’s overview:
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Apparent Depth
Rainbows
Formation of Images by Lenses
Anatomy of the Human Eye
Laser as seen on
TV and movies
Real Laser
Real Laser
Shining Through
a Cloud
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Next week’s reading is Knight Chapter
23, Sections 23.7 – 23.8. You will not be
tested on this material this semester, but it
may be part of the final exam.
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A www.masteringphysics.com Problem Set
on Chapter 23 (up to 23.6) is due on
Friday at 5:00PM. It is the last problem
set of the semester
Course Evaluations in Tutorial this week!
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Your chance to officially evaluate Professor
Harrison and me is this week during tutorial.
Anti-Calendar and will form part of my tenurereview in 2009.
You participation and honest comments are
appreciated – we will read them in the
summer after the marks have been
submitted.
Second Representative Assembly Friday!
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Friday, Dec.2 at 3:00 PM in MP606
One or two “representatives” from each tutorial
group are invited. (Please select yourselves
during tutorial.)
Refreshments will be provided!
I will be there and I’m interested in hearing
your thoughts on issues of communication and
structure of this course.
Professor Strong will be there – she’s your
next prof!
Now Posted on the web site:
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Solutions to last week’s written problem set
Room assignments for next week’s Test.
Find out what room on campus you will be
writing in, based on your tutorial group. Click
on “Test 2” on the main course web site.
Apparent Depth
Apparent Depth
Dispersion
Light going through a prism bends toward
the base
Rainbows
Rainbows
Rayleigh
Scattering
I scattered  
4
Converging Lens
Focal length, f
NOTE: Focal length is defined
for initially parallel rays.
Focal Point
Diverging Lens
Negative
Focal length, -f
Virtual Focal
Point
Rays appear to emerge
from Virtual Focal Point
Diverging rays through a Converging Lens
Focal length, f
This follows from the principle of reversibility.
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