Physics 212 Lecture 22, Slide 1

1
Physics 212 Lecture 22
2
Music

• Who is the Artist?
• Lizz Wright
• Erykah Badu
• Sade
• Cassandra Wilson
• Diane Reeves

Why? Guilty Pleasures??? I
know they all say that her voice is thin,
BUT.. It does sound good esp Please send me
someone to love thats why I bought it (Irma
and Tracy??) p.s. All the choices (except Sade)
have been at Jazzfest
3
(No Transcript)
4
Things you identified as difficult
-intensity and pressure of EM -I didn't quite
understand the whole poynting vector thing. -I'm
confused by the part about how this makes me
money. -do we have new lecture note books?
-polarization -Hey Mats, are you Canadian?
It's aboot time we find out the truth! )
So I know quite a few good newfie jokes eh
5
the concept of posting preflights/prelectures the
day before they're due when the standard has been
to post them "on Thursday of the week before the
lecture." not fair, bro. No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides found.
PreLecture slides are posted on Thursday of the
week before the lecture.No slides
6
High Q Haiku
A double E's friend But don't make sense to
others Miss two-eleven
The world is narrow Lacking harmony and depth My
Q is too high
Double Dog Dare You can do better write any
physics Haiku and Ill show (it as long as
you're not a potty-mouth)
7
(No Transcript)
8
Waves Carry Energy
9
Waves Carry Energy
Why do these look so similar ??
10
Intensity energy delivered per unit time, per
unit area
(U energy)
Area A
Length c dt
Sunlight on Earth I 1000J/s/m2 1
kW/m2
11
If it has energy and its moving, then it also has
momentum
Analogy from mechanics
12
Disk
13
(No Transcript)
14
Because Dp is twice as big when the light is
reflected (just like in mechanics)
15
Poynting Vector
Just another way to keep track of all this -
Its the same thing as I but it has a direction
its just a convenience
16
CD
Wavelength is equal to the speed of light divided
by the frequency.
17
Doppler Shift
ve if they are approaching
-ve if they are separating
f
f
v
f
or
f
v
18
ve if they are approaching
-ve if they are separating
As long as b ltlt 1
So
19
Police radars get twice the effect since the EM
waves make a round trip
20
A)
B)
C)
CD
A) You want to lower the frequency of the waves
hitting your eyes, so the Doppler effect is such
that moving away from the source will reduce the
frequency.
B) Running towards the iclicker will blueshift
it, making the frequency appear to increase.
Since radio waves have a lower frequency then
visible light, this is what is needed to make it
visible
C) Wavelength is equal to the speed of light
divided by the frequency.
21
Wave - Particle Duality
E-M waves are actually made up of individual
particles called photons (I think of them as
little bullets)
Each photon has elements of both waves E B
fields polarization zero mass and
of particles discrete energy E hf
hc/l discrete momentum p h/l
h 6.63e-34 J-s
22
Wave - Particle Duality
h 6.63e-34 J-s
Sunlight on Earth I 1000J/s/m2 1
kW/m2
Example
Suppose l 500 nm, then E hf hc/l 4
x10-19 J for each photon
Must have 2.5 x 1021 such photons hitting every
m2 every second
23
Exercise
An electromagnetic wave is described by where
is the unit vector in the y direction.
24
Exercise
An electromagnetic wave is described by
25
Exercise
An electromagnetic wave is described by
Wave moves in negative z-direction
26
Exercise
A certain unnamed physics professor was arrested
for running a stoplight. He said the light was
green. A pedestian said it was red. The
professor then said We are both being truthful
you just need to account for the Doppler effect !

• As professor approaches stoplight, the
  frequency of its emitted light will be shifted
  UP
• The speed of light does not change
• Therefore, the wavelength (c/f) would be
  shifted DOWN
• If he goes fast enough, he could observe a
  green light !

27
Follow-Up
A certain unnamed physics professor was arrested
for running a stoplight. He said the light was
green. A pedestian said it was red. The
professor then said We are both being truthful
you just need to account for the Doppler effect !
c 3 X 108 m/s ? v 5.4 X 107 m/s