Table Of Content• •
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BERKELEY GRADUATE EXAM QUESTIONS
Ninety Minuteso f Shante but a P/1Dfo r tire Resto f YourL ife!
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DMITRY BUDKER & \.~I
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ALEXANDER 0. SUSHKOV
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ILLUSTRATED BY VASILIKI DEMAS
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PHYSICS ON YOCR FEET:
BERKELEY GRADUATE EXAM QUESTIONS
Physics on Your Feet:
Berkeley Graduate Exam Questions
or
Ninety Minutes of Shatne
but a PhD for the Rest of Your Life!
Dmitry Budker
University of Cahfornia, Berkeley, USA and
Johannes Gutenberg University, Mainz, Germany
Alexander 0. Sushkov
Harvard University, Cambridge, MA, USA
Illustrated by
Vasiliki Demas
OXFORD
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First Edition published in 2015
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To those who are not afraid to ask and those brave enough to answer ...
Preface
How this book came about
In May 2010, the Physics Department of the University of California at Berkeley where
the two of us, at different times, had been Ph.D. students, abandoned the Preliminary
Oral Examinations, a.k.a. oral prelims, for the first-year graduate students, thus breaking
a 60-year long tradition.
In fact, oral examinations were offered at the Berkeley Physics Department much
earlier, however, their most recent format and scope more or less settled by 1950,
as described by A. C. Helmholz in his History of the Physics Depart1nent. 1950-1968
(Helmholz, 2004).
The Berkeley prelim was a scary experience for those of us on the "receiving end
(A.S.)," and a half-day semi-annual chore for those administering the test (D.B. did this
from Fall of 199 5 through Spring of 201 O; he "missed" taking the oral prelims as he
entered the Berkeley Physics graduate program in 19 89 as a continuing student, but has
had his share of oral examinations elsewhere). Nevertheless, the two of us strongly feel
that this has been extremely useful for the students, providing them, perhaps, the first
"real-life" scientific-communication experience, and giving an opportunity to look at the
beautiful world of physics in some approximation of completeness.
It has also been a truly rewarding experience for the faculty member (D.B.). One
learned a lot from the brilliant students, and from the wise colleagues asking truly in
teresting and profound questions. Some of the material of this book is drawn from the
notes taken by D.B. at the exams over the years, as well as from the questions collected
by the students and passed as an exam-preparation aid "generation to generation."
The origin of the content of the book, therefore, has a collective nature, and we are
extremely grateful to the members of the Berkeley physics faculty who have generously
allowed us to use their ideas. Unfortunately, many of our sources are no longer alive to
ask for permission. We remain in deep gratitude to Professors David Judd, Gil Shapiro,
Ronald Ross, and, indirectly, many others.
So what is the point of the book now that the Berkeley orals are no more? We hope
this collection will be useful to students ( of all ages and everywhere) who wish to refresh
and/or test their knowledge of physics, and also to students at the universities that still
administer orals. And there are always written prelims, qualifying exams, even at Berke
ley (at least, for now). The level of the readers we primarily aim at is upper-division
undergraduates and first-year graduate students, although some of these problems will
certainly be enjoyed by postdocs and distinguished physics faculty, looking for a fun
break from or an unexpected contribution to their research.
viii Preface
We have had a lot of fun writing up the problems for this book, and we would like
our readers to share this joy (rather than stress out about the upcoming exam, which is
unproductive). We are greatly assisted in this by the eye-pleasing drawings prepared by
our skillful illustrator, Dr. Vasiliki (Vicky) Demas.
A bullet with Mass M is fired with velocity
v on.to a wooden. block) an.d gets stuck in. the
process. It loses kin.etic en.er9y of half W\v2-.
The question. is: what happen.s to the other half?
Other books
There are several other collections of problems with the scope and goals partially
overlapping with ours. Among these are the following.
• Scattering and structures by Povh and Rosina (2005), which is a lovely collection
of problems for the German oral Diploma and Ph.D. exams with emphasis on
quantum phenomena.
• A guide to physics problems by Cahn, Mahan, and Nadgorny (1994), which is a
wonderful collection of written examination problems, also supplied with many
delightful cartoons (not to mention the most insightful physics).
• An impressive multi-volume Problems and solutions set by a group of Chinese au
thors (Zhang, Zhou, Zhang, and Lim, 1995; Lim, 1998; Bai, Guo, Lim, 1991;
Lim, 2000) compiled by the Physics Coaching Class at the University of Science
and Technology in China as a guide for preparation to Ph.D. exams at major Amer
ican universities. While this collection appears to be very useful, we find the choice
of questions and style of solutions to be substantially different from our own.
