## Sample Physics GRE test - comments welcome

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YF17A
Posts: 94
Joined: Sat Aug 30, 2008 4:42 am

### Sample Physics GRE test - comments welcome

Hi all,

A couple weeks ago I mentioned that I was planning on writing a GRE book including full-length sample tests. I'd like to invite you all to review the problems and solutions of one of the tests we've written:

http://physicsgreprep.wikidot.com/local ... 01.0.0.pdf
http://physicsgreprep.wikidot.com/local ... 01.0.0.pdf

Ideally, if you have 3 hours to kill and want to take the test in exam conditions, that would be awesome. But even if you only have time to glance over the problems and solutions, any comments would be welcome. I would ask that you at least attempt a problem before looking at the solutions, lest you get thrown off by our explanations in the event that we're totally and completely wrong. Some things we're particularly interested in:

* How does the distribution of difficulty levels match that on the real test?
* How about the distribution of problem types? Were there any types of problems that showed up on your test but were conspicuously absent from ours?
* Were any problems particularly GRE-like, or particularly NOT GRE-like (as in, crap you'd find in the purple book)? This applies especially to the "specialized topics" questions.
* Did the selection of answer choices make any of the problems particularly trivial? We don't mind if one or two of the questions you have to work out all the way through, because that seems pretty realistic, but if for several of the questions there are so many obviously wrong answer choices that you don't actually have to solve the problem, that's an issue.
* Were the solutions helpful? Keep in mind there will be review material later, so we don't go into great detail with respect to content, but we do want the solution to be as clear as possible once someone reads the answer key.
* Any ambiguities, possible misinterpretations, etc. of any of the problems.

ali8
Posts: 100
Joined: Sat Aug 29, 2009 8:20 am

### Re: Sample Physics GRE test - comments welcome

Hi

I am not a physics graduate so I won't comment, but since I plan to take the PGRE
I want to encourage you on what you are doing, and I'll be waiting for the full 'book'

physicsworks
Posts: 80
Joined: Tue Oct 12, 2010 8:00 am

### Re: Sample Physics GRE test - comments welcome

Well done, but:
#7,8,49: too many "specific heat" questions for one test
#9: add $$k>0$$ into the text
#11, 97: two "phase, group velocity" questions for one test --- unlikely
#15: good remake of Griffiths' Problem 3.34 in EM book. However, as you may know, the exact solution to this problem should take into account relativistic and field retardation effects (in fact, your answer differs form the correct one by more than 10%, I guess). So I would add something like "ignore these effects"
#17: from Griffiths' QM book, but OK. I would have mention the normalized eigenfunctions $$\psi_n(x) = \sqrt{\frac{2}{L}}\sin{\left(\frac{\pi n}{L} x\right)}$$. No one need to remember this on the PGRE.
#18: Free energy on the PGRE? Maybe, but I doubt (the problem itself is easy, of course)
#20: maybe too "heavy" for the PGRE, although there is a quicker way to choose from available options
#21: see #20
##29,10: Two calculations of the moment of inertia in one test? Unlikely.
#31: Too many calculations. (However, if you've studied problems from Griffiths, you can do this more quickly and less painfully)
#39: too "heavy"
#46: Confusing picture (m or M?)
#47,9: Two similar problems in the same test. Unlikely
#58: too "heavy"
#60: too "heavy"
#62: good one, but you need to specify what $$\delta(\mathbf{r})$$ means (for those who don't know)
#64: too "heavy"
#73: nice problem. I've seen it somewhere before
#74,10: two calculations of almost the same thing $$\int r^2 dm$$ with different $$\rho$$. Unlikely
#77: add $$(ct,x,y,z)=(2,1,1,0)$$
##82,94,36,20: too many Lagrange formalism. Add Hamiltonian mechanics!
##83,84,17: maybe too many square wells
#88: not GRE-like

How about the prep text? When are you planning to show at least one chapter from it?

YF17A
Posts: 94
Joined: Sat Aug 30, 2008 4:42 am

### Re: Sample Physics GRE test - comments welcome

Thanks, this is great. I think you're absolutely correct about the repeats of similar material within the same test, we should fix that (and move some of the repeated problems to different sample exams). And your comments about 9, 15, and 46 are right on.

I wonder about your characterization of "heavy" problems, though. I definitely remember at least two or three problems that required some substantial algebra, which can of course be narrowed down by a clever look through the answer choices. I'm thinking of #20-21 (my test had a problem about the Hamiltonian for a hemisphere, which is not too different), 58 (just basic kinematics with a lot of algebra), and 64 (same). I think problem 39 is debatable, but if you take a look at the solution key, one can eliminate all but two answers just by logical reasoning, so I think it's OK.

On a similar note, I think the GRE definitely assumes knowledge of the normalized square well eigenfunctions and the definition of $$\delta(r)$$. Anyone who's taken the test recently want to weigh in on this?

physicsworks
Posts: 80
Joined: Tue Oct 12, 2010 8:00 am

### Re: Sample Physics GRE test - comments welcome

YF17A wrote:On a similar note, I think the GRE definitely assumes knowledge of the normalized square well eigenfunctions and the definition of $$\delta(r)$$. Anyone who's taken the test recently want to weigh in on this?
Well, take a look at questions 51-53 from GR 9277 test. Also, I remember from my two real exams that ETS provides you with this kind of stuff.

WhoaNonstop
Posts: 853
Joined: Mon Sep 21, 2009 1:31 am

### Re: Sample Physics GRE test - comments welcome

YF17A wrote:Anyone who's taken the test recently want to weigh in on this?
I always thought the r was hiding from the delta.

I briefly glanced over the test and I think it looks pretty well done. Surprised actually. If I get the chance I'll look into it more myself.

-Riley

YF17A
Posts: 94
Joined: Sat Aug 30, 2008 4:42 am

### Re: Sample Physics GRE test - comments welcome

By the way, the solution to problem 5 is hilariously wrong. My apologies. If anyone wants to suggest another problem that gets at the same idea (exchange forces being a significant contribution to atomic binding energies), please feel free.

physics_auth
Posts: 163
Joined: Sat Jul 18, 2009 7:24 pm

### Re: Sample Physics GRE test - comments welcome

YF17A wrote:Hi all,

A couple weeks ago I mentioned that I was planning on writing a GRE book including full-length sample tests. I'd like to invite you all to review the problems and solutions of one of the tests we've written:

http://physicsgreprep.wikidot.com/local ... 01.0.0.pdf
http://physicsgreprep.wikidot.com/local ... 01.0.0.pdf

Ideally, if you have 3 hours to kill and want to take the test in exam conditions, that would be awesome. But even if you only have time to glance over the problems and solutions, any comments would be welcome. I would ask that you at least attempt a problem before looking at the solutions, lest you get thrown off by our explanations in the event that we're totally and completely wrong. Some things we're particularly interested in:

* How does the distribution of difficulty levels match that on the real test?
* How about the distribution of problem types? Were there any types of problems that showed up on your test but were conspicuously absent from ours?
* Were any problems particularly GRE-like, or particularly NOT GRE-like (as in, crap you'd find in the purple book)? This applies especially to the "specialized topics" questions.
* Did the selection of answer choices make any of the problems particularly trivial? We don't mind if one or two of the questions you have to work out all the way through, because that seems pretty realistic, but if for several of the questions there are so many obviously wrong answer choices that you don't actually have to solve the problem, that's an issue.
* Were the solutions helpful? Keep in mind there will be review material later, so we don't go into great detail with respect to content, but we do want the solution to be as clear as possible once someone reads the answer key.
* Any ambiguities, possible misinterpretations, etc. of any of the problems.

----------------------------------------------------------------------
Few remarks upon (maybe) superficial look on your effort:

Remark # 1:
You should moderate the level of most of your questions ... especially those which require integrations and so on ... . PGRE doesn't usually require more than some algebra (very scarcely differentiation and integration but at a kindergarden level!)

Remark # 2:
Some topics are way far from the stuff to be studied for the test. I don't need to go into details ... but I spotted few questions ... (ok I will mention the one with graphene ... nobody is supposed to know the dispersion relation for graphene ... instead try to motivate somebody use a dispersion relation to calculate something else ... average occupation number or something ... but this is again kind of overkill ... same for the questions about effective potential!). If you consulted physics olympiads for the construction of questions this can happen ... (I talk in general here!)

Remark # 3:
You should include more diverse experimental physics questions (other than scattering and detection of particles) - at least oscilloscopes etc. One question looks pretty much like the one appearing in an old test with two detectors in the upper atmosphere but it doesn't matter ... (just to make little bit of fun here ...) ... same for question # 17 ... .

Remark # 4:
PGRE questions don't seem to encompass many different phenomena of physics (in one question) ... questions usually focus on simple phenomena or combinations of a couple of them.

Remark # 5:
Reduce statistical mechanics questions ... include more thermodynamics.

Remark # 6:
Keep in mind that the committee calls for memorization of some very basic stuff ... therefore students are required to apply more often than not very basic formulae. If you want to create a hard problem make it conceptually difficult don't overburden it with calculations!

Remark # 7:
Remove repetition of "examined stuff" ... true ... too much BE condensation ... too many problems involving "elementary particles"!

Remark#8:
If you want to use ETS PGRE questions (such as the one with Compton, photoelectric and pair production cross sectios question ...) use all of your talent to modify that ... (to avoid plagiarism!).

Just these few remarks from my side.
Physics_auth
Last edited by physics_auth on Tue Jul 05, 2011 6:37 am, edited 1 time in total.

physics_auth
Posts: 163
Joined: Sat Jul 18, 2009 7:24 pm

### Re: Sample Physics GRE test - comments welcome

physicsworks wrote:
YF17A wrote:On a similar note, I think the GRE definitely assumes knowledge of the normalized square well eigenfunctions and the definition of $$\delta(r)$$. Anyone who's taken the test recently want to weigh in on this?
Well, take a look at questions 51-53 from GR 9277 test. Also, I remember from my two real exams that ETS provides you with this kind of stuff.
One very good text with all formulae included (needed also for PGRE) is the following:
"Handbook of physics" from
Walter Benenson, John Harris, Horst Stocker & Holger Lutz, Springer.
It's more than comprehensive ...

Physics_auth

physicsworks
Posts: 80
Joined: Tue Oct 12, 2010 8:00 am

### Re: Sample Physics GRE test - comments welcome

Agree with physics_auth
One very good text with all formulae included (needed also for PGRE) is the following:
I was talking about YF17A's preparation text that he announced here. P.S. I'm aware of the book you've mentioned and I think it is not as good (for the PGRE!) as one might think at first glance.

physics_auth
Posts: 163
Joined: Sat Jul 18, 2009 7:24 pm

### Re: Sample Physics GRE test - comments welcome

One very good text with all formulae included (needed also for PGRE) is the following:
I was talking about YF17A's preparation text that he announced here. P.S. I'm aware of the book you've mentioned and I think it is not as good (for the PGRE!) as one might think at first glance.[/quote]

@ Suprised that a graduate student has so much time to prepare a "preparation text" plus physics tests ... one test alone requires quite a few days of hard effort ... (the committee consists of around 6+ people who construct the questions and revise them again and again ... and here there are only two people doing all this work!). ... good luck then.

@ The book I mentioned is more of a formulary than a preparation textbook ... one could consult that for jotting down some stuff to be memorized or for a final look of something.

physics_auth
Posts: 163
Joined: Sat Jul 18, 2009 7:24 pm

### Re: Sample Physics GRE test - comments welcome

YF17A wrote:Hi all,

A couple weeks ago I mentioned that I was planning on writing a GRE book including full-length sample tests. I'd like to invite you all to review the problems and solutions of one of the tests we've written:

http://physicsgreprep.wikidot.com/local ... 01.0.0.pdf
http://physicsgreprep.wikidot.com/local ... 01.0.0.pdf

Ideally, if you have 3 hours to kill and want to take the test in exam conditions, that would be awesome. But even if you only have time to glance over the problems and solutions, any comments would be welcome. I would ask that you at least attempt a problem before looking at the solutions, lest you get thrown off by our explanations in the event that we're totally and completely wrong. Some things we're particularly interested in:

* How does the distribution of difficulty levels match that on the real test?
* How about the distribution of problem types? Were there any types of problems that showed up on your test but were conspicuously absent from ours?
* Were any problems particularly GRE-like, or particularly NOT GRE-like (as in, crap you'd find in the purple book)? This applies especially to the "specialized topics" questions.
* Did the selection of answer choices make any of the problems particularly trivial? We don't mind if one or two of the questions you have to work out all the way through, because that seems pretty realistic, but if for several of the questions there are so many obviously wrong answer choices that you don't actually have to solve the problem, that's an issue.
* Were the solutions helpful? Keep in mind there will be review material later, so we don't go into great detail with respect to content, but we do want the solution to be as clear as possible once someone reads the answer key.
* Any ambiguities, possible misinterpretations, etc. of any of the problems.