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Intuition and the PGRE

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  • Thread starter tburke2
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I am in my third year of ungrad physics and am preparing to take the physics GRE. I've never really memorized formulas or needed to regurgitate anything besides the most basic mathematical axioms. I have learned physics almost completely intuitively, I have a pretty bad memory for exact formulas or equations. I try to explain a concept in words and relate it to earlier concepts and justify why. When calculations are needed I usually just re-derive the equation or look it up if I'm feeling lazy. This has worked very well for me so far (sometimes I just have to accept ideas in things like quantum or relativity without understanding why) but I'm running into a real problem preparing for the PGRE. I have about as many formulas memorized as a high schooler taking basic physics and I certainly don't have enough time to derive or even really think about the questions. Does anyone have any suggestions? I feel like memorization is not the way physics education should be approached but I doubt grad school admissions would be sympathetic.
 

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  • #2
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Most people are in the same boat as you - knowing the system is flawed, but still forced to jump through the hoops. Fortunately, intuition can help one rule out some (if not all) of the incorrect answers on most questions - dimensional analysis and limiting cases will carry you further than you think. It's not so important to memorize exact equations as it is to memorize forms of equations - you might now remember the exact form of the Fermi-Dirac and Bose-Einstein distributions, but you might remember that the former has addition in the denominator and the other has subtraction, and that would help you more than you know.

Unfortunately, some of the pGRE is just purely random knowledge that can't be derived in the 3 minutes you have per problem.
 
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I know I am not alone in saying that contrary to popular belief, (unless the PGRE has changed a lot in the last 15 years) , dimensional analysis, and limiting cases are not likely useful to exclude bad choices. The PGRE authors are too smart for that. Some pGRE is random knowledge, but if it is truly random, your luck is as good as anyone else.

I would definitely work on any old exams you encounter.

I feel similarly. My school posed physics exams where typically 15 minutes to 30 minutes per problem could be taken, and they were very difficult problems. These were not the kind you could answer in 3 minutes.

Much as you are not going to like this answer, it is important to develop a good memory not only for equations, but also for commonly used constants (to save time on the exam). It is good to memorize Planck's constant, Boltzmann's constant, mass and charge of electron. A proton is 1838 times as heavy as an electron. etc.

For what it is worth, I have looked at some grad school applicants using the internet. You probably do this too. It is clear that many very selective grad schools do not count the pGRE highly. GPA is more important for most schools.
 

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