physics 1230: light and color ivan i. smalyukh, instructor office: gamow tower, f-521 email:...
TRANSCRIPT
Physics 1230: Light and ColorIvan I. Smalyukh, Instructor
Office: Gamow Tower, F-521Email:
Phone: 303-492-7277
Lectures: Tuesdays & Thursdays,
3:30 PM - 4:45 PMOffice hours:
Mondays & Fridays, 3:30 PM – 4:30 PM
TA: Jhih-An Yang [email protected]
Class # 2
2
Using iClickers
• Everyday: swap clicker code to DC• Wait for 1st clicker question to open• Hold down On/Off Switch 4 seconds• Flashing blue light: hit D C• Type in Answer.
you’re set for rest of class period
• DO NOT TURN OFF CLICKER FOR CLASS (o.w. repeat above for any new clicker question)
A Light-ning Blitz through the course material
3
Let’s see some of the major things we’ll cover in the class.
4
Light rays and what we “SEE”
Straight-line paths and what enters the eye.
5
Electromagnetic spectrum
c = f
Wavelength
Frequency
Speed of light
6
Electromagnetic waves can have any wavelengthScientific notation is useful!
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Shadows, reflection, refraction – Ch. 2
8
Lenses and mirrors – Ch. 3
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Lenses and mirrors – Ch. 3
Precise mathematics let’s you DESIGN lens systems.
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Photography – Ch. 4
Image recording - digital
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The Eye – Ch. 5
Visual systems in other creatures.
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Optical instruments – Ch. 6
Telescopes
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The “Very Large Array” ‘near’ Socorro, NM.
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Optical instruments – Ch. 6
Microscopes
Robert Hooke’s circa 1660
Modern laser confocal
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Your eyes can play tricks on you – Ch. 7
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Visual Processing – Ch. 7
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Visual Processing – Ch. 7
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Color – Ch. 9
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Color perception – Ch. 10
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Color perception – Ch. 10
The sum of the two number is:
A) 18 B) 20 C) 23 D) 25
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Scattering & Polarization – Ch. 13
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Holography and Lasers – Ch. 14 & 15
Break for 7th inning stretch.
Something to ponder during the stretch:
WHY (and how) do we see things?
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Favorite answers:
Because…
Because there is LIGHT…
Because we have EYES…
Because creatures that see tend to survive…
We want to understand these things
First goals of the course:
Understand enough about light to be able to talk about it. Develop our first model for how light behaves and how
we SEE things.
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Disappearing glass rods…
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http://www.youtube.com/watch?v=7hOZJL_bEPQ
http://www.youtube.com/watch?v=pNWCB_GoQA4
Cloaks of invisibility?
26http://www.youtube.com/watch?v=mcPzCb7TlZ8&NR=1
What do you already know about light?
•Spectrum
•Wave and particle properties
•Source of energy momentum
•Fast speed
•Straight line unless it interacts
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Please, make a list with :
Laser
Flashlight
Lightbulb
Incident ray from a light bulb
MANY reflected rays comefrom all parts of Alex, including
his nose - a diffuse object
Bob sees Alex's nose because a reflected light ray enters Bob's eye!
Light rays are invisible unless they enter directly into our eye or are scattered bysmoke, fog or some object into your eye!
Rays bounce when they reflect off a mirror or shiny surface
Mirror
• This is called specular reflection.
• How is it different from diffuse reflection?
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To understand light better we need to know about Waves
• Electric fields• Magnetic fields• Light is an ‘electromagnetic wave’
E
B
QUALITATIVE things about electric forces
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A) There are two types of chargeB) There is only one type of chargeC) There are more than two typesD) None of the above.
A) Like charges attractB) Like charges repelC) Opposite types repelD) Depends on the situation.
And opposites attract
QUANTITATIVE statement:
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Coulomb’s Force Law:
2qQF kqQr
q
Qr
Constant of nature.
Depends on the charges
distance
What is the force that q feels from Q?
A question:
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You are given three numbers, a, b, and c. True or false: The combination of numbers
abc
A) TRUE
B) FALSE
ba
cis always equal to:
Experiment: Try some actual numbers, like a=2, b=3, c=4 and test it.
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You are given four numbers, a, b, c, and d. Which of these are valid ways to rewrite ab
cdA)
B)
C)
D)
E)
ba
cd1
abcd
1d
abc
All of the above
None of the above
Experiment can be valuable here too…
QUANTITATIVE statement:
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Coulomb’s Force Law:
2qQF kqQr
q
Qr
Constant of nature.
Depends on the charges
distance
What is the force that q feels from Q?
Useful to rewrite things:
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Coulomb’s Force Law:2qQF k
qQr
Which is another way to write this force law?
A)
B)
C)
D)
E)
2qQF q kQr
2 2qQF kq Qr r
2qQF kq Q
r
None of these
All of these
The universe divides into two parts:
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Coulomb’s Force Law:
2qQF q kQr
Property of the local THING, say YOU.
Properties of the rest of the universe.
We Say: qF qEr ELECTRIC FIELD due to the rest of the universe.
Suppose we have 3 charges:
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The force felt by q …
2 2 2 2
1 2 1 21 2 1 2qQF k k q k k qE
qQ qQ Q Qr r r r
q
Q1r1
A) Can still be F=qEB) Cannot be F=qEC) MAY be F=qE if the
charges are in a line.D) Something else
happens.
Q2
r2
Electric Fields
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The charge value. Properties of
the rest of the universe.
We Say that charges feel a force:
qF qEr
ELECTRIC FIELD due to the rest of the universe.
What do you already know about magnetism?
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A) Magnets come with only a north poleB) Magnets come with only a south poleC) Magnets come with both a north and
south pole.D) Depends upon the type of magnet.
A) Like poles attractB) Like poles repelC) Opposite poles repelD) Depends on the situation.
GUESS WHAT: The universe produces Magnetic Fields too.