modern physics 2007 trimester 3

   "quiz"  corrections
Jun 4
Jun 5
Jun 6
final exam
 scheduled Modern Physics final

you can use
1) your notes
2) your returned work (homework, lab books, quizzes, etc)
3) probably your textbook (but likely only book covers and appendix B)

because of limited desk space on the third floor (for an open notes, homework, etc.) test, we will use
bryan 439
(modern classroom)

bryan 436
(non-topics classroom)

4th bryan 1st  lab

in addition to the biology lab (bryan third floor) areas

(4th bryan 2nd lab will be for students doing the course eval on the computer)

 come early to 4th floor if you want a 4th floor table all to yourself
make-up final for conflicts

room on 4th bryan to be decided at the time
today from
3:30 to 5 pm

last homework
[3 (20, 21)] has been graded and is available for pick-up in the black box

make sure that the STRAY PAPERS folder does not have any of your papers... if you have papers in the envelope tomorrow, you will not be able to start the test on time

total homework score possible
(this should match your summary in the back of your notes) = 815

(high score in the class was 761; median was 652)

at 1 pm, I will make one last check of the homework, stray papers, and lab books to make sure that everything is out of my box...
there are still approximately 50!) modern physics papers, homeworks, labs, etc that need to be picked up

if your stuff is still there at 1 pm, you will not be able to be seated on the 4th floor rooms (see above) until I make another check at 1:25 pm... so you may have to start the exam slightly late

 my intentions are to have all the E2 labs graded by today at 6 pm

solutions are posted now

and especially questions 16 and 17 .... make sure you understand the physics...
there was a lot of scary incorrect physics written in some lab books...
also  check out the background sources....
pages 527 - 530 should have been very helpful in understanding lab E2
quizzes quiz corrections have been checked....

pick them up from me in person today

show & tell
check my office door to make sure that my record is accurate



will probably have to wait till the exam period, although it might be ready tonight if i finish the lab grading as planned

course evaluation

May 28
May 29
May 30
May 31
June 1
students return 
 assume we are doing lab
the last class 
 the "stray paper" envelope is now too heavy to be suspended on my bulletin board by a mere push pin.... it now has to rest its bottom on the table
(sort of like students late for class watching the show and tell)...
 therefore, some MP students suggested that if those papers are still there in the folder today at noon, then anyone who doesnt have papers in the folder can come and choose 1 of the stray papers still in the folder and get the points credit on that paper....
since the points (and the homework) are clearly of no value to the person who originally wrote that paper

a tempting idea!

what we'll do
in class

look at the results
(current, stopping voltage)
predictions for the particle model of light
look at the results
(current, stopping voltage)
predictions for the wave model of light....

make sure you know the expectations for several of the boxes

(always done
before class)
 finish 3(4) on the photoelectric effect

finish the Feynmann handout

(by 5 pm)



 2nd test corrections due

May 21
May 22
May 23
may 24
May 25
 shortened classes

not all people have taken either the test or quiz
what we'll do
in class

begin discussion of quantum theory:

how light went from behaving like a wave to behaving like a particle

finish talking about light as a wave

can you reproduce the math in the Feynmann article in section 1-3 and relate it to the homework assignment (wave function) we got back yesterday?

finish talking about the meaning of the x-ray section....

first you'll need to explain exactly what physics was used to get the equations on page 89

and once we've done that, what are the lessons we should take away from the behavior of x-rays described in this section?

same question about the 2 pages of the photoelectric experiment in the new reading

(always done
before class)

Jiggling the Cosmic Ooze

"A Giant Takes on Physics Biggest Questions"

video: Betting Billions on Physics

graphics: Capturing Primordial Fire

slideshow:  The Large Hadron Collider


bring an equation, written down on paper that you will hand in, that describes (models) either one of the waves pictured in figure 3.2....

if you use symbols (other than those labeled in the picture, and surely you will), make sure these are labeled as well on a copy of the picture that you also will turn in on the same paper
 the Feynmann article, at least the first 3 sections
 section 3(5) of the text, but just the half up to "the compton effect"

be able to explain the physics of  equation 3.25a

and the physics of the two equations on page 89

also, why is this section in this chapter?
what is the experimental evidence telling us about light?
 first 2 pages of the photoelectric experiment section (3.4)

be able to describe the experiment in clear English

what are the input variables (what things can we vary in the experiment) and what are the output variables (what things can we measure)

(by 5 pm,
unless noted)
submit 2 questions inspired by the above "frontiers of physics" reading via this web page (link coming soon)....

questions get more credit  the more interesting and the more unique they are
(i.e., don't share questions)

by 7 am today
bring several examples to class
(written down on paper or in your notes)
of phenomena
that can only be explained by light behaving like a wave

you should be able to come up with 4, by doing some research
surely it has occurred to you that the 2 headlights on a car are an example of the double-source experiment!

let's assume  the lights are monochromatic....
wavelength = 500 nm...

the double-source experiment says that there will be alternating bands of dark and light in front of you as you drive....
could a deer be hidden in a "dark" band so that you don't see it?
could you be responsible for killing Bambi?

find out, by calculating the difference in distance between two successive "brights" at a distance of 20 meter in front of the car (where the deer will be).... I presume that you know a reasonable distance between headlights..

2) from the data collected in class on thursday, determination the wavelength of the laser; make sure you use the graphical methods learned in intro physics and include a matching table that goes with the graph....
if you havent done matching tables, there is a description in the lab guide in your lab books (and we have extra copies, since i have your books)

please compare this to the standard wavelength of the He-Ne laser (which we used) and which is given in your modern textbook, and make sure that you are within 5%

i am assuming that the CD track separation is cultural literacy (there is an industry standard, originally determined by SONY)



May 14
May 15
May 16
May 17
May 18
 quiz on chapters 13, 14, and parts of 15 done before this week

you MUST bring YOUR book (you will be allowed to use Appendix B and the front and back covers, but nothing else)....  I will NOT have extra books nor extra copies of the Appendix, etc

you will also be allowed to use YOUR notes, YOUR returned homework and lab work....

EVERYONE MUST turn in the E3 radioactivity lab today after the test
what we'll do
in class

understand rutherford scattering
(the salmon handout)
finish rutherford scattering and apply it to how we know there are quarks inside the nucleus
quark evidence,
and chapter 15

(always done
before class)
 you were supposed to have read 15(8) for
friday, but we didnt get to it... we'll try again

plus read the first 2 pages of the next section (pp. 574-575)

know the "evidence" we have for quarks despite the fact that we have never seen one
the salmon handout on rutherford scattering...
pages 1- 3.5 should be very quick reading

pages 3.5 through 4 you should understand thoroughly....

BEFORE reading the salmon handout, you should come up with a formula for
the scattering angle, as a function of K (alpha kinetic energy), b (the impact parameter) and Z (the charge of the target nucleus)

AND the PHYSICS laws that you used to figure out how 
q depends on these things....

after you do this, then make sure you can follow all of the physics and algebra/calculus on page 4

(there are copies in the black box if you werent in class and no one brought you one)
15(6) on strangeness

15(7) up to "Energy considerations ..."

so you know how particles are discovered, especially when they only live nanonanoseconds or less

and the last 1.5 pages of the salmon rutherford scattering handout....

block C:
is equation 4(6) testable? why or why not?

block D:
we have a lot to still do, since we did so little yesterday....
what happened to F sin phi ? what's this angular momentum stuff? and more....
please take the time to make sure you follow the physics (and math) line by line
 we still have yet to address the reading from wednesday...
we also need to finish section 15(9)

there may be a short quizlet on any of that reading

i think we ended both classes with the question of

why was the predicted the hadron/muon creation
wrong by exactly 3?

what didnt we count?
(in both classes, the first guess was that we didnt all the quarks, but that didnt work out)


(by 5 pm)

 14(41, 59)
bring to class. on paper to hand in:
an estimate of the mass of the omega
(with work shown... please try to do better than the simplest, most trivial model)

can you estimate a

show/draw explicitly the uds triangle symmetry in the spin-0 meson hexagon (fig 15.11b, p. 572 ) in the same way that we did in class for the spin-3/2 baryons (fig. 15.12)... then identify the quark composition of the 3 particles at the center
use the rutherford scattering results to find the angle that light (treated as a classical, Newtonian  particle) bends when gravitationally influenced by the sun

a) first make a translation table
(from coulomb scattering to gravitational bending... what letters change to what letters)

b) plug in the relevant numbers, and solve for the bending angle in seconds of arc
(see page 56); if you're not within a factor of 2 of the value the book quotes on page 56, please come get help
lab E3 due if possible
(if you want me to check it and see if you did it correctly before friday's quiz)....
.... otherwise it's due today,
although i will probably let you keep your lab books to study for the test
 E3 due today....
if it's not in the box at 4:30 pm.... it won't get graded... this applies to ALL lab books, even the ones I looked at thursday
NPR this morning has a story on how to build an atomic bomb with "boy-scout technology"

New York Times this morning has "A Giant Takes on Physics Biggest Questions"

video: Betting Billions on Physics

graphics: Capturing Primordial Fire

slideshow:  The Large Hadron Collider

properties of particles 

May 7
May 8
May 9
May 10
May 11
what we'll do
in class
last friday we discussed

1) neutrino production
(in sun & atmosphere)

2) neutrino detection
(almost finished)

so today is
3) what happens (and why and how) in between?

last chance for questions on neutrino transformation,
based on what we finished up yesterday....

you'll tell me all about nuclear fission reactors....
the stuff that we made the list of in class today:

fuel.... what is it?
why that?
why do we do enrichment?
how do we do enrichment?

critical mass.... why do we need one? why can't any mass do it?

what do they do?
why do we need them?

control rods.... ditto

chain reaction....
what sustains it?

we do a radioactivity lab in addition to finishing nuclear fission:

see yesterday's questions, plus

how do we extract the KE (of the radioactive decay)?

why do we need to cool the water?

what do we use for shielding?

everything about fusion:

what conditions are necessary?

advantage and disadvantages compared to fission?

if we (on earth) have done fusion, why havent we done sustained fusion?

how are we trying to overcome this obstacle?

leftovers questions (mostly about confinement: where's the physics??) from fusion...

make sure that you can explain the confinement, etc etc using the currents and magnetic fields shown

how do we know hadrons are made of quarks, if we have never seen a quark?
(always done
before class)
Weighing in on the Neutrino

be able to tell the ratios of

nm, down)/N(ne, down)

N(ne, down)/N(ne, up)

N(nm, down)/N(nm, up)

where N = number

"up" = moving up into the detector from below ground

"down" = moving down into the detector from the atmosphere

and what conclusions you can draw from each ratio

 14(3 - 5 up through the bottom of p. 515)
14(1-2, and finish 5) 
15(1,2 and 3) should be a brief review

you've already read 15(4,5)

15(8) is new

(by 5 pm)
1) 13(3)

2) (from Physics, Cutnell and Johnson, 4th edition): The shroud of Turn is a religious aftifact known since the Middle Ages.  In 1988 its age was measured using the radiocarbon dating technique,
 which revealed that the shroud could not have been made before 1200 AD.
Of the carbon -14 nuclei that were present in the living matter from which the shroud was made, what percentage remained in 1988?
13(33), the problem i thought i had assigned for monday


14(22, which requires that you do 21)

14(27) and the problem that we started in class:  prove that -- in a collision of an initially moving particle n with
an initially stationary particle p -- the maximum KE is transfered when the two particles have the same mass
(hint: you will need to write the KE transferred in  terms of only
the masses of the two particles and the initial speed of particle n)
lab E3 
block D only:

make sure that you have picked up your E3-checked lab book from the back lab room and placed it in the correct stack at the back of the classroom 


April 30
May 1
May 2
May 3
May 4
 there may be a walk-around quiz today in class on conservation laws in beta decay

what we'll do
in class

master beta decay

(know the 3 kinds)

you'll tell me:

what the 2 basic physics equations of radioactivity are

which decays are important for dating things tens of years old,  thousands of years old, and billions of years old?

learn how to do radioactive decay problems
talk about the evidence for neutrino mass
(see reading below)

please know the evidence for why physicists think neutrinos have mass
(see reading below)

(always done
before class)
  bottom of p. 487 - bottom of p. 489
 13(4) on the laws of radioactivity and radioactive dating


examples 13.10 and 13.11,
pp. 490-491
pp 491-496

more on radioactivity;
new stuff on gamma decay
pp. 558-559
(solar neutrinos; this experiment won  half of the 2002 Nobel Prize in Physics)

Weighing in on the Neutrino
(on atmospheric neutrinos;
this experiment  won  the other half of the 2002 Nobel Prize in Physics)...

how did we figure out that neutrinos made in the atmosphere were decaying (changing into something else) before they got to the ground?

pp. 598-599
(on identifying neutrinos)
1 done in block C
0 done in block D
(3 expected per week;
the course is now more than 50% over; you should already have done 1)

(by 5 pm)


13(52, 46)

 top quark lab due
E2 nuclear shielding lab due

questions 16 and 17 are the meaty explanation questions....answers should be 1 - 2 pages each
Chart of the Nuclides

where to find the answer to all things nuclear (binding energy, decay products,  half-lifes, KE released/decay, isotope abundances)

ALL nuclear physics answers must be checked here for full credit

no more than 3 neutrinos can exist

deadline is today for showing me the in-class work from tuesday
(energies released in decay, v/c for beta, etc.;
it was different in different blocks)
the first neutrino image of the sun

the old Kamiokande detector

latest atmospheric muon-neutrino results

Sudbury Neutrino Observatory
detection  physics

modern physics pages for april 2007
modern physics pages for march 2007