E. P. KHALFIN. Physics Problem Book, GTTI, 1932, 208 pp., price 2 rub. 65 kopecks.

At present there is a large number of manuals on the courses in general physics taught in our higher schools on the book market (Berliner, Grimmsehl, Joffe, Lecher, Michelson, etc.), but the number of problem books in physics is extremely limited. Maller’s problem book, published in 1923, has long been sold out, despite a number of shortcomings and its overall dryness; Afanasiev’s problem book, intended for technical schools, is too elementary for technical higher educational institutions, but too “technical” for other higher educational institutions that have an abbreviated program (medical, biological, geographical departments of universities and pedagogical institutes); there remains only the problem book by Walter, Kondratyev, and Khariton, which in recent years has gone through a number of reprintings and is used almost everywhere, despite the fact that it is designed for the serious physics course of the Leningrad Polytechnic Institute and is too difficult for educational institutions with an abbreviated course.

Therefore, the publication of a new problem book is quite timely. However, upon becoming acquainted with Khalfin’s problem book, the reader is left with a feeling of dissatisfaction, caused above all by the unsuccessful attempt to provide, in 200 pages, not only material for exercises but also a synopsis of a physics course.

Undoubtedly, in order to make the student’s work easier it is useful to supply particular sections of a problem book with a compilation of the most important formulas, as is done, for example, in the problem book by Walter, Kondratyev, and Khariton. But such a compilation, intended only for reference, cannot, and indeed should not, take the place of a physics textbook.

In the problem book under review, however, in addition to problems there is a theoretical part containing, as the author writes in the preface, “all the information necessary for solving problems.” At the same time this information is presented in the form of ready-made formulas, while some of the formulas are derived in detail. The selection of material and the completeness of the exposition appear insufficiently justified. Thus, the Clapeyron equation (p. 13), whose derivation should be known from the secondary-school course, is derived over two pages, while the fundamental equation of the kinetic theory of gases is not derived at all; the derivation of the formula determining the work of isothermal expansion of a gas is printed in small type (p. 22), while the work of adiabatic expansion (p. 80) and Poisson’s equation (p. 77) are given entirely without derivation.

On p. 153 the law for the series connection of resistances is formulated (without derivation); on pp. 159–160, on its basis, the law for the distribution of potential between resistances connected in series is derived, and on p. 164 a detailed derivation is given of the law for the parallel connection of conductors.

Restricting ourselves to only these few (but by no means all) examples, we should also note that on p. 62 Kopp’s rule for determining the heat capacities of chemical compounds is mentioned, an example is given, and not a single problem is provided. It is not clear why this rule, which has no wide application, should be mentioned in a problem book (in a physics textbook such a mention may perhaps be useful, but we are not considering this synopsis as a textbook).

On the other hand, Kirchhoff’s rule, which is extremely valuable in practice,

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which facilitates the calculation of all kinds of circuits, is passed over in complete silence, and in the section on electromagnetic induction not a word is said about the direction of the induced electromotive force. Not a single line is devoted to the magnetic circuit and the phenomenon of self-induction (true, these questions are not touched upon in the problems either, but such ignoring of them can hardly be considered expedient).

Insufficient attention is also paid to various systems of units (the electromagnetic system is entirely absent) and to questions of dimensions, although, as teaching practice shows, these very important questions always cause students difficulty.

Not having at hand the program of the metallurgical higher technical educational institution in which the author teaches, it is difficult to object to the distribution of material adopted by him. As for the general character of the problems, however, for technical higher educational institutions it must be regarded as too elementary. Not a single problem requires the application of higher mathematics; the overwhelming majority of problems require the simple substitution of numerical values into formulas, and this substitution is further facilitated by the fact that the problems immediately follow each formula derived (or given without derivation), so that the student does not even have to think about choosing the appropriate formula, but merely has to substitute the numbers and carry out the calculation. Those problems which require some consideration are almost all supplied with detailed solutions. Therefore, even after solving a large number of problems from this problem book, the student will at best remember the basic formulas, but will not learn to think physically and consciously apply these formulas in even somewhat complicated cases.

Finally, the book contains a number of careless formulations and outright errors; some of them are cited below.

On p. 20 the force of 1 g is taken as equal to 982 dynes; on p. 68 it is already equal to 981 dynes, and on p. 136 even to 1016 dynes, since 640 megadynes are equated to 630 kg.

On p. 141 mention is made of the capacitance of a sphere surrounded by another sphere (instead of speaking of the capacitance of a system of two spheres); on p. 155 a definition of resistivity is given from which it follows that resistivity is measured in ohms; on p. 169 charge is transferred “from one potential to another,” and on p. 188 a magnetic field arises around ... a magnetic moment.

All these roughnesses, which could easily have been avoided, create an even more unfavorable impression.

Summing up all that has been said above, it must be acknowledged that Khalfin’s problem book is capable only to a very slight degree of filling the gap in our educational literature on physics.

N. Malov