Ink Sandwiches, Electric Worms and 37 Other Experiments for Saturday Science , Neil A. Downie Johns Hopkins U. Press, Baltimore, MD, 2003. $45.00, $18.95 paper (334 pp.). ISBN 0-8018-7409-2, ISBN 0-8018-7410-6 paper
At the University of British Columbia, we run a fourth-year physics course in which students who are interested in a teaching career learn how to build physics demonstrations and present them in schools. Thus we are always on the lookout for suitable projects that are eye-catching, inexpensive, and yet pedagogically solid. Ink Sandwiches, Electric Worms, and 37 Other Experiments for Saturday Science by Neil Downie has many good ideas.
Most of the projects Downie presents were developed over years of involvement with a Saturday morning children’s club in his hometown of Guilford, England. The projects are pitched at a level such that a physicist can reproduce them in a few hours’ work at home with commonly available materials. Alter-nately, with some supervision, a student could also build the projects for a science fair or undergraduate course. The broad topics Downie covers are mechanics (linear, rotational, vibrational, and chaotic), fluids, sound, electromagnetism, electro-chemistry, and electronics. Each chapter of the book consists of an introduction, building instructions, explanation, and a more detailed science and math section. The science will appeal to a broad age range. Fairly young audiences (elementary and middle school students) will like the demonstrations; with the addition of numerical analysis, they are also appropriate for grades 11 and 12 and for first-year undergraduates. Occasionally, the science and math section provides a note of uncertainty as to exactly why we see what we see—something I quite like.
A couple of simple examples in the book are worth mentioning. One is the generation and measurement of standing waves in a coffee cup. The vibrations are produced by a small electric motor with an eccentric weight on the axle, and a vane and photodiode measure the frequency. The demonstration contains a lot of physics, which only detailed measurements can reveal.
Another example demonstration involves balancing balls in a vertical air stream. In that experiment, Downie describes in detail a variation I had not seen before: balancing a column of several balls of increasing size. I’m not sure, though, that I agree with the stability analysis presented. The author says that a Ping-Pong ball that moves off axis rotates and is brought back by the Magnus force. My experience with somewhat heavier squash balls is that they refuse to rotate, even when suspended in an almost horizontal air stream. Surely the stability of the balls lies in the acceleration of the air, and the subsequent drop in pressure, as the air tries to get around each ball. This said, I am puzzled why squash balls will not rotate even in an axially asymmetric flow. Such is the nature of many of these “simple” effects, especially in fluids, that defy straightforward analysis.
There is a “Hints and Tips” section at the back of the book that covers information about suppliers, data loggers, and the use of spreadsheet programs. If I could make a suggestion for the second edition, it would be to vastly expand this section. For example, coverage on data loggers gets a mere two lines. A multichannel analog-to-digital converter for a personal computer now costs less than $100, and many sensors are also available for a few dollars each. Such obtainable electronics equipment, coupled with the ubiquity of PCs and spreadsheet programs, makes computer data acquisition and graphical analysis accessible to even the most strained high-school science budgets. A few pages of tutorial on how to set up data acquisition and graphical analysis for experiments would be very valuable.
Knowing something of the often ex-hausting business of science outreach and how long it takes to produce a five-minute demonstration, I recognize the huge effort that must have gone into this book. Downie is a particle physicist turned consultant and the author of a recent textbook on industrial gases; so everything that went into Ink Sandwiches—the development, presentations, and writing—must have been done during his leisure time. The book is a job well done, and I recommend it for anyone trying to get physics across to non-specialist audiences.
