PHYSICS
DEMONSTRATIONS

A Sourcebook for
Teachers of Physics

Julien Clinton Sprott

In the matter of physics, the first lessons should contain nothing but what is experimental and interesting to see. A pretty experiment is in itself often more valuable than twenty formulae extracted from our minds.* -- Albert Einstein

*A. Moszkowski, Conversations with Einstein, page 67, Horizon Press (1970).

A NOTE TO THE READER

This preliminary, partial manuscript is a very early, incomplete version of a published book. The much more extensive, heavily illustrated, and up-to-date, full-color, 300-page version was published by the University of Wisconsin Press in 2006 and can be ordered here. You may copy this material for your personal use. Further distribution or commercial use requires permission of the author.

DISCLAIMER

The demonstrations and other descriptions of procedures and use of equipment in this book have been compiled from sources believed to be reliable and to represent the best opinion on the subject as of 1990. However, no warranty, guarantee or representation is made by the author as to the correctness or sufficiency of any information herein. The author does not assume any responsibility or liability for the use of the information herein, nor can it be assumed that all necessary warnings and precautionary measures are contained in this publication. Other or additional information or measures may be required or desirable because of particular or exceptional conditions or circumstances, or because of new or changed legislation. Teachers and demonstrators must develop and follow procedures for the safe performance of the demonstrations in accordance with local regulations and requirements.

See the essay Injuries in School/College Laboratories in USA by Dr. R. Standler at
http://www.rbs2.com/labinj.htm which discusses the law in the USA about injuries to pupils or students in school or college science laboratories.

Preface

Acknowledgments

Bibliography

Selected Vendors of Scientific Demonstration Equipment

Selected Vendors of Audiovisual and Computer Materials

Other Related Materials

1. MOTION

1.1 Bowling Ball Pendulum
1.2 Come-back Can
1.3 Bicycle Wheel Gyroscope
1.4 Guinea and Feather Tube
1.5 The Monkey and the Coconut
1.6 Ballistics Car
1.7 Pail of Water
1.8 Inertia Balls
1.9 Revolving Ball and Cut String
1.10 Toy Rockets
1.11 Rolling Chain
1.12 Moving Spool
1.13 Stack of Cards
1.14 Wilberforce Pendulum
1.15 Reaction Time
1.16 Beaker and Tablecloth
1.17 Inclined Plane
1.18 Coupled Pendula
1.19 Random Walk
1.20 Chaotic Pendula

2. HEAT

General Safety Considerations
2.1 Liquid Nitrogen Cannon
2.2 Collapsing Can
2.3 Carbon Dioxide Trough
2.4 Exploding Soap Bubbles
2.5 Hero's Engine
2.6 Model Geyser
2.7 Magdeburg Hemispheres
2.8 The Impossible Balloon
2.9 Boiling with Ice
2.10 Freezing by Evaporation
2.11 Nonburning Handkerchief
2.12 Liquid Nitrogen Cloud
2.13 Heat Transmitter
2.14 Ethanol Vapor Explosion
2.15 Heat Convection
2.16 Exploding Balloons
2.17 Smoke Rings
2.18 Bell Jar
2.19 Liquid Nitrogen
2.20 Kinetic Theory Simulator
2.21 Firehose Instability
2.22 Dripping Faucet

3. SOUND

Safety Considerations with Sound
3.1 Breathing Helium and Sulfur Hexafluoride
3.2 Oscilloscope Waveforms
3.3 Doppler Effect
3.4 Bell in Vacuum
3.5 Wave Speed on a Rope
3.6 Beat Frequencies
3.7 Breaking a Beaker with Sound
3.8 Flame Pipe
3.9 Ultrasound

4. ELECTRICITY

Electrical Safety Considerations
4.1 Jacob's Ladder
4.2 Van de Graaff Generator
4.3 Tesla Coil
4.4 Faraday Cage
4.5 Gas Discharge Tube
4.6 Wimshurst Electrostatic Generator
4.7 Exploding Wire

5. MAGNETISM

5.1 Levitated Ball
5.2 Magnet with Cathode Ray Tube
5.3 Can Crusher
5.4 Jumping Ring
5.5 Superconductors

6. LIGHT

Laser Safety Considerations
6.1 Spiral Light Guide
6.2 Water Light Guide
6.3 Tubeless Television
6.4 Optical Illusions
6.5 Talking Head
6.6 Pepper's Ghost
6.7 Prism Rainbow
6.8 Laser Gun
6.9 Laser Beam
6.10 Fluorescence
6.11 Twinkling Stars

PREFACE

The teaching of physics is clearly enhanced by the use of demonstrations. Visual examples of abstract concepts aid immeasurably in their mastery. They also provide an opportunity to illustrate the scientific method and to teach the student to relate experimental observation to scientific theory. Experiments represent the means by which scientific knowledge has advanced so rapidly in modern times. Finally, not to be underestimated, the use of demonstrations makes the learning of physics much more enjoyable!

This book is a compilation of many of the demonstrations that have been used at the University of Wisconsin - Madison in the teaching of elementary physics over the years as well as a number of demonstrations that I have developed for use in a series of popular lectures, "The Wonders of Physics," aimed at the general public and children in particular. Included also are a number of demonstrations that have been suggested and used by friends or colleagues. All of the demonstrations have been thoroughly tested in a classroom setting or before an audience of the general public.

To write a book that purports to describe all possible physics demonstrations would be a formidable task since the discipline of physics is so all-encompassing. Instead, I have selected demonstrations that are especially dramatic or provocative, as well as some of the standard demonstrations that can be presented in unusual ways. In part, this reflects my feeling that it is necessary to get the attention of the students and convince them that physics is interesting before any real learning can occur, but also because there seems to be little help available for the instructor who wants to improve the quality of his or her presentation. This book is thus not meant to contain a complete set of demonstrations for the teaching of elementary physics, but rather to provide the instructor with ideas for new demonstrations and better ways to present old ones.

There are many other books on physics demonstrations listed in the bibliography. A number of these are far more complete than the book I have written. Some are quite old and do not make use of the advances in instrumentation of the past few decades. I have attempted to complement these works by concentrating less on the description of the apparatus, much of which is now well-known and commercially available, but more on techniques for bringing them to life and generating interest in them. For example, I have included historical anecdotes and other commentary to add to the interest and have suggested alternate uses for the apparatus. I have provided brief explanations of those facets of the demonstrations that may not be obvious to a trained physicist or physics teacher. I have also emphasized safety more than is usual in such books.

The usual style of books on physics demonstrations is to list the important concepts and to give a large number of demonstrations to illustrate each one. The majority of these demonstrations, though pedagogically sound, are not very suitable because they require close, careful measurement, or they are not easily visible to a large audience, or they are simply not very exciting. They belong in a laboratory, not as part of a lecture. I have taken a different approach, in that I describe the demonstrations first and then mention the many physics concepts that are illustrated. This departure from the usual teaching mode in which the concepts are introduced sequentially has proved especially effective for informal presentations to the public and to children who have not studied physics.

When I cause a soap bubble filled with methane gas to explode by touching a lighted candle to it (section 2.4), no one in the audience is asleep, and I can proceed to discuss thin films, surface tension, Archimedes' principle or any number of other related topics with their full attention. There are certainly more "scientific" ways to demonstrate the variation of the speed of sound with the density of a gas than by breathing helium and sulfur hexafluoride (section 3.1), but few students will forget the result, and it is hard to resist wanting to know the explanation. The talking head (section 6.5) and Pepper's ghost (section 6.6) are extraordinarily elaborate demonstrations of the rather simple ideas of the total and partial reflection of light off the interface between two media, but when one contrasts this method with the way such concepts are usually taught, it is no wonder why physics has the reputation of being dry and uninteresting.

It is my hope that this book and the accompanying video cassette tapes of "The Wonders of Physics" will also inspire teachers of physics to take the demonstrations beyond the classroom to the general public. All that is required is a notice to the media and a carefully planned, fast paced presentation of 20 to 30 demonstrations. Such a program never fails to attract an enthusiastic audience. The public is hungry for entertainment with educational value, and demonstrations such as described in this book will appeal to adults and children alike.

My own program is a yearly event with the best of the old demonstrations and about half new ones each year. The program is repeated several times in the space of a week or two to accommodate the demand. This is preferable to using a larger hall in which it might be difficult to see many of the demonstrations. The schedule avoids saturating the interest and permits adequate time to develop dramatic new demonstrations. The demonstrations for the general public generate a continual demand for special presentations to schools and other groups.

This book is intended for use by those with a good knowledge of physics, and thus the scientific principles involved are not explained in great detail. Many elementary physics texts are available to fill this need.

The apparatus required for the demonstrations varies considerably in complexity. Some of the demonstrations can be done with equipment available at home or from a local hardware store. Others are best constructed from components found in a well-equipped physics laboratory or available from specialized mail-order vendors. In such cases, I have tried to provide references to articles that describe the construction or have outlined the important considerations that must go into the design, but I have largely avoided a cookbook approach to the assembly of the required apparatus since there is usually great leeway in the design depending upon the resources available. Some of the more complicated demonstrations are available ready-made from vendors of scientific apparatus, and in such cases I have included possible sources in a footnote.

Although most of the demonstrations are completely safe, a few involve potential dangers and should be carried out only by someone knowledgeable in physics as well as experimental technique. The dangers include burns from heat, caustic chemicals and high frequency electricity; frostbite from handling cryogenic materials; cuts especially from broken glassware; explosions from high pressure gases and volatile substances; implosions from evacuated glassware; asphyxiation; electrocution; eye damage from lasers; and exposure to radioactivity. The major hazards are mentioned, but a large dose of caution and a respect for the forces of nature are essential.

I am indebted to many people in the preparation of this work. The book is patterned after Chemical Demonstrations by Professor Bassam Shakhashiri whose example and encouragement also inspired "The Wonders of Physics" lectures. Many of the demonstrations have been handed down within the University of Wisconsin Physics Department for so many years that their origin is unknown. Others have come from the suggestions of friends and colleagues too numerous to mention. To all who have contributed, I offer my sincere thanks.

Julien Clinton Sprott
Professor of Physics
University of Wisconsin
Madison, Wisconsin
April 1996

ACKNOWLEDGMENTS

Durlin C. Cox, Resonance Research, Inc., Baraboo, WI

Donald W. Kerst, University of Wisconsin, Madison, WI

Lawrence S. Lerner, California State University, Long Beach, CA

Kenneth C. Maas, University of Wisconsin, Madison, WI

Edward E. Miller, University of Wisconsin, Madison, WI

Mary C. Moebius, Verona Middle School, Verona, WI

Paul D. Nonn, University of Wisconsin, Madison, WI

Bassam Z. Shakhashiri, University of Wisconsin, Madison, WI

Elizabeth Steinberg, University of Wisconsin, Madison, WI

Teri L. Vierima, Wisconsin Radiation Protection Council, Madison, WI

BIBLIOGRAPHY

Amerongen, C. V. The Way Things Work, Simon and Schuster: New York (1967).

Arons, A. B. A Guide to Introductory Physics Teaching, John Wiley & Sons: New York (1990).

Blasi, R.C., Ed. Physics Fun and Demonstrations with Professor Julius Sumner Miller, Central Scientific Company: Franklin Park, Illinois (1974).

Bolton, W. Physics Experiments and Projects, Pergamon Press: Oxford (1968).

Brown, T. B., Ed. Advanced Undergraduate Experiments in Physics, Addison-Wesley Publishing Company: Reading, Massachusetts (1959).

Bulman, A. D. Model-Making for Physicists, Crowell Company: New York (1964).

Bulman, A. D. Models for Experiments in Physics, Crowell Company: New York (1966).

Cherrier, F. Fascinating Experiments in Physics, Sterling Publishing Company: New York (1978).

Edge, R. D. String and Sticky Tape Experiments, American Association of Physics Teachers: College Park, Maryland (1981).

Ehrlich, R. Turning the World Inside Out, Princeton University Press: Princeton, New Jersey (1990).

Esler, W. K. Modern Physics Experiments for the High School, Parker Publishing Company: West Nyack, New York (1970).

Freier, G. D., and F. J. Anderson. A Demonstration Handbook forPhysics, 2d ed., American Association of Physics Teachers: Stony Brook, New York (1981).

Greenberg, L. H. Discovery in Physics, Saunders: Philadelphia (1968).

Herbert, D. Mr. Wizard's Supermarket Science, Random House: New York (1980).

Herbert, D., and H. Ruchlis. Mr. Wizard's 400 Experiments inScience, Revised Edition, Booklab: North Bergen, New Jersey (1983).

Hilton, W. A. Physics Demonstration Experiments at William JewellCollege, William Jewell College: Liberty, Missouri (1971).

Ingersoll, L. R., M. J. Martin and T. A. Rouse. Experiments inPhysics, McGraw-Hill Book Company: New York (1966).

Liem, T. K. Invitations to Science Inquiry, Ginn Press: Lexington Massachusetts (1981).

Lunetta, V. N. and S. Novick. Inquiring and Problem-Solving in thePhysical Sciences: A Sourcebook, Kendall/Hunt: Dubuque, Iowa (1982).

Joseph, A., P.F. Brandwein, E. Morholt, H. Pollack and J. F. Castka. A Sourcebook for the Physical Sciences, Harcourt, Brace and World: New York (1961).

Mark, H. M. and N. T. Olson. Experiments in Modern Physics, McGraw-Hill Book Company: New York (1936).

Meiners, H. F., Ed. The Ronald Press Company: New York (1970).

Meiners, H. F., W. Eppenstein, R. A. Oliva and T. Shannon. LaboratoryPhysics, John Wiley & Sons: New York (1987).

Melissinos, A. C. Experiments in Modern Physics, Academic Press: New York (1966).

Nokes, M. C. Demonstrations in Modern Physics, William Heinemann Ltd.: Melbourne (1952).

Richards, K. Science Magic with Physics, Arco Publishing Company: New York (1975).

Robinson, H. A., Ed. Lecture Demonstrations in Physics, American Institute of Physics: New York (1963).

Rutherford, F. J., et. al. The Project Physics Course Handbook, Holt, Reinhart and Winston: New York (1978).

Shakhashiri, B. Z. Chemical Demonstrations, The University of Wisconsin Press: Madison, Wisconsin, Vol 1 (1983), Vol 2 (1985).

Sutton, R. M., Ed. Demonstration Experiments in Physics, McGraw-Hill Book Company: New York (1938).

Taylor, C. The Art and Science of Lecture Demonstration, American Institute of Physics: New York (1988).

VanCleave, J. P. Teaching the Fun of Physics, Prentice-Hall Press: New York (1985).

Walker, J. W. The Flying Circus of Physics--With Answers, Interscience Publishers, John Wiley and Sons: New York (1977).

Walker, J. W. The Physics of Everyday Phenomena, Freeman: San Francisco (1979).

SELECTED VENDORS OF SCIENTIFIC
DEMONSTRATION EQUIPMENT

American Science Center, Incorporated
601 Linden Place
Evanston, IL 60202
(312) 475-8440

American Scientific Products
1430 Waukegan Road
McGraw Park, IL 60085
(312) 689-8410

Arbor Scientific
P. O. Box 2750
Ann Arbor, MI 48106-2750
(313) 663-3733

Carolina Biological Supply Company
2700 York Road
Burlington, NC 27215
(919) 584-0381

Central Scientific Company
11222 Melrose Avenue
Franklin Park, IL 60131-1364
(302) 451-0150

Cole-Parmer Instrument Company
7425 North Oak Park Avenue
Chicago, IL 60648
(312) 647-7600

Daedalon Corporation
P. O. Box 2028
35 Congress Street
Salem, MA 01970-6228
(617) 744-5310

Edmund Scientific
101 East Gloucester Pike
Barrington, NJ 08007
(609) 573-6257

Fischer Scientific
4901 W. LeMoyne Street
Chicago, IL 60651
(312) 378-7770

Frey Scientific Company
905 Hickory Lane
P. O. Box 8101
Mansfield, OH 44901-8101
(419) 589-9905

Fry Interfacing
2618 Buena Vista Drive
Greeley, CO 80631
(303) 330-5055

General Science Materials Company
10123 Crosby Avenue
Garden Grove, CA 92643
(714) 534-0985

Hampden Engineering Corporation
99 Shaker Road
East Longmeadow, MA 01028
(413) 525-3981

Innovative Technology, Incorporated
2 New Pasture Road
Newburyport, MA 01950
(508) 462-4415

Klinger Educational Products Corporation
112-19 14th Road
College Point, NY 11356
(718) 461-1822

Lenox Laser
One Green Glade Court
Phoenix, MD 21131
(301) 592-3106

Merlan Scientific Limited
247 Armstrong Avenue
Georgetown, ON L7G 4X6
Canada
(416) 877-0171

MMI Corporation
2950 Wyman Parkway
P. O. Box 19907
Baltimore, MD 21211
(301) 366-1222

Nasco
901 Janesville Avenue
Fort Atkinson, WI 53538
(414) 563-2446

PASCO Scientific
10101 Foothills Boulevard
P. O. Box 619011
Roseville, CA 95661-9011
(916) 786-3800

Rudolph Instruments, Incorporated
40 Pier Lane
Fairfield, NJ 07004
(201) 227-0139

Sargent-Welch Scientific Company
7300 North Linder Avenue
P. O. Box 1026
Skokie, IL 60077
(312) 677-0600

Schoolmasters Science
745 State Circle
P. O. Box 1941
Ann Arbor, MI 48106
(313) 761-5072

TEL-Atomic, Incorporated
P. O. Box 924
Jackson, MI 49204
(517) 783-3039

SELECTED VENDORS OF AUDIOVISUAL AND
COMPUTER MATERIALS

The Academic Software Library
Box 8202
North Carolina State University
Raleigh, NC 27695-8202
(919) 515-7447

Agency for Instructional Technology
Box A
Bloomington, IN 47402-0120
(812) 339-2203

April Computing Executive Limited
Chestnut Farm
Tarvin Road
Frodsham, Ches. WA6 6XN
United Kingdom
(0928) 35868

Astronomical Society of the Pacific
390 Ashton Avenue
San Francisco, CA 94112-1722
(415) 337-1100

Blue Sky Associates
9 Cardinal Street
Winchester, MA 01890
(617) 729-3465

Cambridge Development Laboratory, Incorporated
214 Third Avenue
Waltham, MA 02154
(617) 890-4640

Computer Friends, Incorporated
14250 N. W. Science Park Drive
Portland, OR 97229
(503) 626-2291

Computer Teaching Corporation
1713 South State Street
Champaign, IL 61820
(217) 359-6363

Cross Educational Software
P. O. Box 1536
504 East Kentucky Avenue
Ruston, LA 71270
(318) 255-8921

Educational Images Limited
P. O. Box 367
Lyons Falls, NY 13368
(315) 348-8211

EME Corporation
P. O. Box 2805
Danbury, CT 06813-2805
(203) 798-2050

EuroTel, Incorporated
P. O. Box 2031
Corvallis, OR 97339
(503) 753-0539

Films for the Humanities & Sciences, Incorporated
P. O. Box 2053
Princeton, NJ 08543-2053
(609) 452-1128

Focus Media, Incorporated
839 Stewart Avenue
P. O. Box 865
Garden City, NY 11530
(516) 794-8900

Great Plains National
P. O. Box 80669
Lincoln, NE 68501-0669
(402) 472-2007

H & R Corporation
401 East Erie Avenue
Philadelphia, PA 19134-1187
(215) 426-1700

Hi-Tech Designs
1654 164th Avenue
San Leandro, CA 94578
(415) 278-5132

Image That, Incorporated
151 Bernal Road
Suite 5
San Jose, CA 95119
(408) 365-0305

Insight Press
614 Vermont Street
San Francisco, CA 94107
(415) 826-3488

Kalmia Company, Incorporated
71 Dudley Street
Cambridge, MA 02140
(617) 864-5567

Mallmann Scientific
20250 Jeffers Drive
New Berlin, WI 53146-2522
(414) 549-1773

MECC
3490 Lexington Avenue, North
St. Paul, MN 55126-8097
(612) 481-3500

Media Design Associates, Incorporated
P.O. Box 3189
Boulder, CO 80307-3189
(303) 443-2800

Microphys
1737 West Second Street
Brooklyn, NY 11223
(718) 375-5151

MMI Corporation
2950 Wyman Parkway
P. O. Box 19907
Baltimore, MD 21211
(301) 366-1222

Opportunities for Learning, Incorporated
20417 Nordhoff Street
Chatsworth, CA 91311
(818) 341-2535

Queue, Incorporated
338 Commerce Drive
Fairfield, CT 06430
(203) 335-0906

TriMetrix, Incorporated
444 Northeast Ravenna Boulevard
Suite 210-PT
Seattle, WA 98115
(206) 527-1801

Trinity Software
533 SE Cliff Road
Port St. Lucie, FL 34984
(772) 446-7607

U. V. Process Supply, Incorporated
4001 N. Ravenswood Avenue
Chicago, IL 60613
(312) 248-0099

Wordware Publishing, Incorporated
1506 Capital Avenue
Plano, TX 75074
(214) 423-0090

OTHER RELATED MATERIALS

Videotapes

Video cassette tapes and DVDs of "The Wonders of Physics" containing most of the demonstrations described in this book are available from:

The Wonders of Physics
University of Wisconsin
1150 University Avenue
Madison, WI 53706
(608) 262-2927

The Wonders of Physics Lecture Kit This kit of materials describes "The Wonders of Physics" program in detail. It includes a videotape of "The Wonders of Physics," the PHYSICS DEMONSTRATIONS software, a book explaining the motivational and logistical considerations, and samples of handouts and publicity materials. It is intended as an aid for physics teachers and physicists who want to start similar programs or enhance already existing ones. It can be obtained for $90 postpaid from:

The Wonders of Physics
University of Wisconsin
1150 University Avenue
Madison, WI 53706
(608) 262-2927

Table I

Computer Simulations