The Physics GRE

Here is some information and general advice for the Physics GRE exam. If you have additional advice/resources that you'd like to share with Stanford SPS, please e-mail Flip ( ).

What is it?

The GRE Physics Test, along with the GRE General Test, are the two standardized exams you are required to take throuh ETS to apply to most U.S. graduate programs in physics. The source for official information is the ETS GRE website.

When to Take It?

The GRE Subject Tests are given three times a year in November, December, and April (check the official ETS site for dates). ETS takes about a month to process scores and most graduate school applications are due in December and January, so November is the de facto "last chance" to take the Physics exam. The December test usually conflicts with Stanford's final exams, anyway. If you can adquately prepare, taking the April exam is ideal since you don't have to study for the GRE while preparing grad apps and, in the worst case, can "fall back" on the November exam if you don't do as well as you'd wanted.

Test Logistics

GRE subject tests are paper-based multiple choice exams that are administered at certified testing centers on Saturday mornings. As of the 2005 exams, the closest testing centers to Stanford were Santa Clara and San Jose. You'll probably need a ride to get there. The exam is 100 questions and three hours long. The exams are $130 to take and you can list up to four scholarships/schools to send your scores to for free (it's in your best interest to do this and to keep track of which schools you've sent scores to!). Additional score reports are $15 per report plus a $6 phone service charge.

How to Study

The GRE Physics test is not likely going to be like any other physics exam you've had while you've been at Stanford. While the test is about as long as your standard in-class final, you're not allowed to have any notes or references. Some people interpret this as a requirement to memorize every formula one can get one's hands on, but this isn't necessarily the case. Also, the exam is composed of 100 multiple choice questions--this means you need to identify the correct answer (by whatever means you can) as quickly as possible.

The best way to prepare is to spend a quarter (or most of a quarter) working with a study group of physics colleagues. You should focus almost exclusively on the official practice exams, no other source of problems seems to have representative topics of types of questions. The study group will provide your framework for working out problems, keeping on-schedule (and do keep a strict schedule of practice exams), and providing encouragement.

Official Practice Exams

ETS has the 2001 test available online through their webpage. Additionally, there is an out-of-print ETS book with the 1986, 1992, and 1996 exams. This is being sold at a ridiculous price online, but it is on reserve in the physics library and can be checked out from the physics main office. However, one can do even better than this, the Brandeis physics department appears to have all four of these exams available as PDFs for free online.

These exams contain the types of questions that are the most representative of those on the actual test. The conventional wisdom is that the 2001 exam (GR0177) is the most similar to current tests, while the remaining exams (GR9677, GR9277, GR8677) decrease with difficulty in reverse-chronological order. The '96 exam tends to have more order of magnitude estimation and the '86 exam tends to have more questions that can be eliminated by dimensional analysis.

You should be sure to take all of these exams with enough time to go over them before the test date, with at least one exam under test conditions and ideally spending time on your own repeating all the questions that you've missed.

What You Need to Know

(..."and how well you need to know it.") Perhaps the first thing you should look at after organizing your study group is the breakdown of test questions on the ETS website and on the first few pages of the practice tests. Make sure you are familiar (to some degree) with the sub-topics in each of the main branches of physics tested. It's not likely that you'll be an expert in each of the "specialized topics" but you should be relatively fluent in the subjects that constitute 10% or more of the questions. Here's a rough account of the level at which different topics need to be known:

  1. Classical Mechanics (20%): Most of the questions are at the 40-series level, though you should be familiar with the basics of the Lagrangian and Hamiltonian formalisms. Some Physics 110-level questions on central potentials may show up. You should be more than adequately prepared reviewing out of a book like Marion & Thornton for the advanced topics and your favorite freshman mechanics book for the rest.
  2. E&M (18%): The Physics 120 series provides all of the background information necessary. Most calculations are at the freshman-physics level, though you are expected to know quantitative relations for more advanced topics (e.g. how does the total power radiated by a point source depend on charge?). Griffiths should cover anything you need to know, but most questions are at the level of the 40-series text.
  3. Optics and Wave Phenomena (9%): You should be fine with the 20- or 40-series texts for these topics.
  4. Thermodynamics and Statistical Mechanics (10%): There will be more exams from freshman-level thermodynamics rather than Physics 170-level statistical mechanics. That being said, it doesn't hurt to know what a partition function is and how it works. Again, the 40-series text should suffice except for a basic understanding of statistical mechanics topics.
  5. Quantum Mechanics (12%): If you've taken the Physics 130 series, you'll be insulted at how simple most of the quantum questions are. Most questions are at the level of the Physics 70 text.
  6. Atomic Physics (10%): The best reference for the atomic physics topics is probably the Physics 70 text (I found Beiser, which is what I used for 70, especially useful). Don't be overly concerned by these questions just because you haven't taken an "atomic physics" class.
  7. Special Relativity (6%): Knowing how to do calculations at the Physics 70 level is a must.
  8. Laboratory Methods (6%): Now you can check how much you picked up from Physics 105 and 107. You'll have a couple to a few questions with circuit diagrams, and possible a question or two on lasers, oscilloscopes, and statistics. The circuit diagrams are at the basic E40 level.
  9. Specialized Topics (9%): There isn't too much you can do here. If you've started thinking about what you want to study in graduate school or have spent a summer or two doing research, chances are that you have some background in one or two of these topics. It's not worth it to pick up a book on some other topic (say, astrophysics if you're a condensed matter person or vice versa) with the intent to read the first 5 chapters. Instead, see what kinds of questions pop up regularly on the practice exams and read up on certain topics (always starting with the easiest expositions at a Physics 70-level text!) as you have time.

A good "extended" version of a standard freshman physics textbook (such as the latest extended edition of Halliday and Resnik) tends to be useful to have handy as you're going over problems. (The "extended" sections contain most of the modern physics you'll need.)

Some Tips

Some further (somewhat redundant) bits of advice:


Below is a short list of useful links:

Test Day

Some things to remember on test-day: eat breakfast, bring a snack and something to drink. Three hours is a long exam! Also, be mindful of your own body and don't drink your entire bottle of water right before the test starts. You're not allowed any restroom breaks in the last half hour of the exam.