# Physics Equations for Grad School / Physics GRE Prep

Motivation for asking question: I am planning to take the GRE subject test for Physics.

Question: Can somebody please tell me what are the most important equations I should definitely know and understand completely going into this test and for entering first year Grad School for physics?

(schodinger equation, F = dp/dt, Maxwell Equations, what else?)

Follow up Question: What are some miscellaneous equations that are also important to know?

The phrasing of your question worries me. Learning physics doesn't have anything to do with memorizing equations. If you understand the meaning of an equation, you shouldn't have to memorize it.

• well, sure - I think it goes without saying that one needs to understand what the equations stand for. Nevertheless, in a high pressure situation like the physics GRE exam room, it's to the advantage of the test taker to be able to bust out the infinite square well functions which she's memorized rather than derive them on the spot.
– Jen
Aug 9, 2011 at 2:28
• If the test is well constructed, then there will be no such advantage due to memorization of silly trivia like that. It's been 25 years since I took the test, but I didn't do any memorization of equations for it, and I don't recall that that put me at a disadvantage.
– user4552
Aug 10, 2011 at 16:55
• An example of why this isn't true: From high school until right before the GRE, I never bothered to remember whether it's B = mu H or H = mu B. Then I memorized it for the GRE, and I've never had to look it up again. It just took a bit of mental effort -- very worthwhile. Knowing things like that is very very useful, because if you're calculating or thinking through something, you don't want to have to keep stopping to look up dumb things like that. Even if it only takes 20 seconds to look it up, that's enough to lose your train of thought. Apr 15, 2013 at 16:01
• One Issue in GRE physics is they give 100 question for a period of 170 Minutes, So it is difficult to think slowly and clearly in that sort of a pressured situation. I personally despise the nature of the exam. Apr 15, 2013 at 18:07
• How are rings defined in the GRE Subject Test in Physics?
– BCLC
Oct 25, 2018 at 6:21

The GRE physics exam is partitioned into at least 7 different subject areas, so there are no "singly important" formulae, I'm sorry to report. The breakdown is roughly 20% allocated to E&M and Mechanics, and between 5-15% for Quantum, AMO, Relativity, Lab Methods, etc. There's a wiki page with this breakdown, so this may be a good place to look for formulas.

I would say that a lot of this subject matter is encompassed in advanced undergraduate texts, so hitting a good comprehensive text is a good place to start. Further, the GRE is multiple choice, so get good at eliminating answers that don't make sense for dimensional, scale reasons right off the bat, and consider the strategy of just knowing when not to answer since the grading scheme takes into account the total number of questions answered.

There are various study guide and practice tests available at the ETS Website for free, so this would be a good help, and there is an entire forum available for consult on topics related to graduate school and physics at PhysicsGRE.com. Good luck!!

• Just to echo Jen's comment: get a copy of a past test (available from ETS), and take it under test-like conditions. There's no better way to see what kind of things are on the actual test than to see what kind of things were on an actual test. And there's also probably no better predictor of how you'll do on it. Aug 8, 2011 at 18:48
• Familiarity with the format of a standardized test also tends to increase one's score, even if you just take a sample test immediately beforehand and don't have time to study after that.
– user4552
Aug 10, 2011 at 17:57

Go to a library or a good college town bookstore, look for and browse through "University of Chicago Graduate Problems in Physics" by Cronin, Greenberg & Telegdi. Aim to be familiar with enough ideas and techniques to be able to answer at least half the questions.

• this is overkill Aug 10, 2011 at 15:08
• Yes, it's stretching for a level beyond the immediate need, usually a good thing for intelligent people. Aug 11, 2011 at 15:16

If you are getting started, 70-80% of the GRE is based on freshman physics from any standard textbooks such as Halliday and Resnick, extended version (which means modern physics included). For this, all the equations you are asking about can be found in the summary that follows every chapter. Of course it goes without saying that memorizing the equations is completely useless unless you understand how they are used.

Woan's The Cambridge Handbook of Physics Formulas is very good for preparing for the GRE.

Daniel Beller of Brandeis has put together a nice and reasonably short pdf of the formulae you need to know as "Things to Know for the PHysics GRE".

You can try the formula-and-concept review that I made when I was studying for it in 2005:

http://sjbyrnes.com/studysheet.pdf

(15 page PDF)

I'm especially proud of the mnemonics I came up with, like "In a diamagnet, the magnetic field dies" to remember which one is diamagnetic versus paramagnetic... Or S,P,D,F,G (the angular momentum quantum number labels) can be short for "Some Physicists are Destined to Flunk the GRE" :-P