SECTION ONE: INTRODUCTION FOR WORKSHOP LEADERS
-
Published:1996
Robert J. Reiland, 1996. "INTRODUCTION FOR WORKSHOP LEADERS", Teaching About Magnetism, Robert J. Reiland
Download citation file:
It is common for physics and physical science teachers to avoid the subject of magnetism because they are not comfortable with it. There are at least two obstacles that contribute to this discomfort. The first is that much of the magnetic phenomena that can be investigated in a school laboratory is counter-intuitive. In particular, action-at-a-distance effects and forces are often produced in unexpected directions. Given time, a teacher could produce experiments that would help students around this first obstacle if it wasn’t for the perceived dangers of such experiments. This is the second obstacle. The study of magnetism can, but need not, involve the use of dangerous amounts of electrical energy.
It is common for physics and physical science teachers to avoid the subject of magnetism because they are not comfortable with it. There are at least two obstacles that contribute to this discomfort. The first is that much of the magnetic phenomena that can be investigated in a school laboratory is counter-intuitive. In particular, action-at-a-distance effects and forces are often produced in unexpected directions. Given time, a teacher could produce experiments that would help students around this first obstacle if it wasn’t for the perceived dangers of such experiments. This is the second obstacle. The study of magnetism can, but need not, involve the use of dangerous amounts of electrical energy.
Fortunately, neither of these obstacles is difficult to overcome. Since the counter-intuitive aspects of magnetism do not involve effects frequently observed by students, most student preconceptions are not as firmly held as are those in mechanics. Those preconceptions that do exist can usually be clearly contrasted with the results of experiments which often are so different from expectations that students welcome alternative models and explanations. The second obstacle, the dangers in the use of electricity, can be completely avoided by the use of batteries and the construction of simple pieces of equipment that require little use of energy.
The demonstrations and experiments described in this book have been developed over many years. They involve cheap and simple materials that are commonly available and easy to put together. As much as possible, construction should be done by the students, but its always a good idea to build your own version so that you have a feeling for any difficulties students might have.
The workshop and teaching approach that is suggested is based on my personal observations and research concerning the decisive role that expectations have on our perceptions. Students and workshop participants should often be asked to think about, and preferably put into writing, what they expect to happen before they do an experiment or a demonstration. This approach is becoming more common, but I believe that it does not go far enough. To complete the process students should be asked to suggest alternatives to their expectations.1 This is based on the observation that when a person has a strong expectation of a result, he or she is likely to see this result or one very similar to it even when it does not occur! On the other hand when expectations are made more general by the consideration of alternatives, it becomes more likely that the observer will accurately perceive the effects. Another aspect of this approach is that the first investigations should be qualitative rather than quantitative. Then, as the student has more experience with the phenomena, it becomes appropriate to ask for more detailed, therefore quantitative, hypotheses, and at this level the teacher should be prepared to advance some of these detailed hypotheses or to assist students in refining their own. Hypotheses that might be suggested to students will appear with the workshop activities.
SUGGESTED ACTIVITIES AND DEMONSTRATIONS FOR A WORKSHOP ON “TEACHING ABOUT MAGNETISM”
I. Tell the participants that it is important that students express their hypotheses and consider alternate hypotheses before doing experiments. Brainstorming is an effective way to do this.
II. Time permitting, cover the following Laboratory Activities. Note that the introduction to the set is in the first activity. This is useful for students, but the activity is probably too elementary to cover with teachers in your workshop.
LABORATORY ACTIVITY 2: Seeing Magnetic Fields
This can be done along with Demonstrations and Displays #6 (A Two Dimensional Magnetic Field Viewer) and #3 (A Three Dimensional Magnetic Field Viewer).
LABORATORY ACTIVITY 3: How are Magnetic Fields Produced?
If you are emphasizing qualitative activities, you may want to present only the first part.
LABORATORY ACTIVITY 4: Penetration of Magnetic Fields through Matter
Due to time limitations in a workshop, ask participants to try some of this while doing the previous two activities.
LABORATORY ACTIVITY 5: Electromagnets
LABORATORY ACTIVITY 7: Magnetic Forces on Current Carrying Wires
LABORATORY ACTIVITY 8: Magnetic Forces on Moving Charges
LABORATORY ACTIVITY 11: A Model of Magnetic Domains
LABORATORY ACTIVITY 12: Long Range Repulsion, Short Range Attraction
III. Set up any of the DEMONSTRATIONS AND DISPLAYS that you have materials for. These can be viewed as participants arrive and at lunch time.
IV. You may want to demonstrate PHYSICS CONTEST EVENT #2 (Magnetic Push).
MATERIALS LIST
Item | # needed per group | Activity# used in |
Soft iron bar magnet | 2 | 1, 2, 4, 7, 8 |
1 | 6 | |
Magnetic marbles | 2 | 1, 2, 4, 10 |
6 | 5 | |
12 or more | 11 | |
Glass marbles | a few | 11 |
Horseshoe magnet | 1 | 1, 2, 4, 7 |
Neodymium magnets | 2 | 12 |
Various magnets | 4, 7 | |
Strong l"x2" flat magnets | 1 or 2 | 10, 11 |
Pieces of copper wire | 1 or more | 1, 5 |
Iron filings or powder | sprinkling | 1, 2, 10 |
Paper clips | 1 or 2 | 1, 2, 3, 4, 7, 9, 10 |
about 10 | 5 | |
Bits of wood and plastic | 1 of each | 1 |
Nails | 2 | 1, 4, 5, 10 |
Aluminum foil | 1 sheet | 1, 4 |
Water | 1, 4, 9 | |
Sand, salt and coins | 1 | |
Small blocks or sheet of glass | 1 | 1, 4 |
Sheets of paper | several | 1, 2, 3, 4, 7 |
Sheets of thin cardboard | 1 or 2 | 2 |
Corrugated cardboard | 2 of 5cm × 10cm | 7 |
Small magnetic compass | 1 | 2, 3, 4, 6, 11 |
Tall jars (such as olive jars) or | 1 | 2 |
graduated cylinders | 1 | 2,4 |
Balloon | 1 or 2 | 2,4 |
Vegetable or mineral oil | 2,4 | |
String | 2, 4, 7 | |
Magnet wire - the thinnest | 2 - 4 meters | 3, 5, 7, 8 |
available | ||
Sand paper or steel wool | 3,5 | |
Wire cutters | 1 | 3, 5 |
Knife | 1 | 3 |
Strong soda straw or the wrapped | 1 | 3 |
glass tube from a Project Physics | ||
or PSSC Centripetal | ||
Force Apparatus | ||
Shoe box, 2 liter soda bottle or a block of wood at least 20 cm high | 1 | 3 |
Protractor | 1 | 3 |
Ring stands and clamps | 2 | 3, 4, 5, 6, 7 |
C or D cell batteries | 2 | 3, 4, 5, 7 |
A battery pack | 1 | 3, 5, 7 |
9 volt batteries | 2 | 5, 8, 9, 11 |
The apparatus constructed for Activity 3 | 1 | 4, 7 |
Small wood sheets | 1 | 4 |
Large beaker | 1 | 4, 9, 11 |
Soda straw | 5 | |
Tooth picks | a few | 5 |
Rubber bands | 2 | 5 |
Sticky tape | 5, 7 | |
Ring stand rod or other long steel rod | 1 | 6, 12 |
Solenoid | 1 | 6, 8, 9, 11 |
Low voltage DC power supply (6 - 20 volts maximum) | 1 | 6, 8, 11 |
Oscilloscope | 1 | 8 |
Sewing needle | 1 | 9 |
Thread | 9 | |
Cork | 9 | |
Magic marker | 1 | 11 |
Small cardboard or plastic lids and/or boxes | several | 11 |
Small paper clip box | 1 | 11 |
Steel nuts 0.25” thick | 2 | 12 |
Steel ball bearing 0.5” diam. | 1 | 12 |
Item | # needed per group | Activity# used in |
Soft iron bar magnet | 2 | 1, 2, 4, 7, 8 |
1 | 6 | |
Magnetic marbles | 2 | 1, 2, 4, 10 |
6 | 5 | |
12 or more | 11 | |
Glass marbles | a few | 11 |
Horseshoe magnet | 1 | 1, 2, 4, 7 |
Neodymium magnets | 2 | 12 |
Various magnets | 4, 7 | |
Strong l"x2" flat magnets | 1 or 2 | 10, 11 |
Pieces of copper wire | 1 or more | 1, 5 |
Iron filings or powder | sprinkling | 1, 2, 10 |
Paper clips | 1 or 2 | 1, 2, 3, 4, 7, 9, 10 |
about 10 | 5 | |
Bits of wood and plastic | 1 of each | 1 |
Nails | 2 | 1, 4, 5, 10 |
Aluminum foil | 1 sheet | 1, 4 |
Water | 1, 4, 9 | |
Sand, salt and coins | 1 | |
Small blocks or sheet of glass | 1 | 1, 4 |
Sheets of paper | several | 1, 2, 3, 4, 7 |
Sheets of thin cardboard | 1 or 2 | 2 |
Corrugated cardboard | 2 of 5cm × 10cm | 7 |
Small magnetic compass | 1 | 2, 3, 4, 6, 11 |
Tall jars (such as olive jars) or | 1 | 2 |
graduated cylinders | 1 | 2,4 |
Balloon | 1 or 2 | 2,4 |
Vegetable or mineral oil | 2,4 | |
String | 2, 4, 7 | |
Magnet wire - the thinnest | 2 - 4 meters | 3, 5, 7, 8 |
available | ||
Sand paper or steel wool | 3,5 | |
Wire cutters | 1 | 3, 5 |
Knife | 1 | 3 |
Strong soda straw or the wrapped | 1 | 3 |
glass tube from a Project Physics | ||
or PSSC Centripetal | ||
Force Apparatus | ||
Shoe box, 2 liter soda bottle or a block of wood at least 20 cm high | 1 | 3 |
Protractor | 1 | 3 |
Ring stands and clamps | 2 | 3, 4, 5, 6, 7 |
C or D cell batteries | 2 | 3, 4, 5, 7 |
A battery pack | 1 | 3, 5, 7 |
9 volt batteries | 2 | 5, 8, 9, 11 |
The apparatus constructed for Activity 3 | 1 | 4, 7 |
Small wood sheets | 1 | 4 |
Large beaker | 1 | 4, 9, 11 |
Soda straw | 5 | |
Tooth picks | a few | 5 |
Rubber bands | 2 | 5 |
Sticky tape | 5, 7 | |
Ring stand rod or other long steel rod | 1 | 6, 12 |
Solenoid | 1 | 6, 8, 9, 11 |
Low voltage DC power supply (6 - 20 volts maximum) | 1 | 6, 8, 11 |
Oscilloscope | 1 | 8 |
Sewing needle | 1 | 9 |
Thread | 9 | |
Cork | 9 | |
Magic marker | 1 | 11 |
Small cardboard or plastic lids and/or boxes | several | 11 |
Small paper clip box | 1 | 11 |
Steel nuts 0.25” thick | 2 | 12 |
Steel ball bearing 0.5” diam. | 1 | 12 |
For example, Gerrit L. Verschuur in Hidden Attraction: The History and Mystery of Magnetism suggests that a number of other investigators might have beaten Oersted to the discovery that electric currents produce magnetic field except that their expectations of a specific result caused them all to orient their compass needles perpendicular to their wires, that is, in the direction that the magnetic field produced by the wire must have acted.
SELECTED BIBLIOGRAPHY
Magnetism article citations from THE PHYSICS TEACHER 1979-1995
Magnetism article citations from SCIENTIFIC AMERICAN 1955-1995