TEACHING PHYSICS
Magnetism is a phenomenon that attracts people of all ages. Surprisingly, we know less about peoples’ conceptions of magnetism than we do about other physical phenomena. We report the conceptions of magnetism of a number of groups.
[T]his kind of stone [the magnet] restores husbands to wives and increases elegance and charm in speech.
Moreover, along with honey, it cures dropsy, spleen, fox mange, and burn . . .
.
In the pithy article, ‘Why do I have to study physics?’ Gore (1997) hinted at many reasons; however, magnetism was not explicitly mentioned.
The advice above may provide a cogent reason for studying magnetism: according to Verschur (1993, p 8), it was apparently the view of Bartholomew of England in the thirteenth century.
Magnetism is one of the more fascinating phenomena in science. Today, magnetic materials are everywhere. It certainly is a topic that students generally find attractive.
However, we need to understand their thinking if we are to capitalize on this attraction.
The phenomenon of magnetic attraction has been know since ancient times because of the behaviour of a variety of magnetite known as lodestone.
On occasion, magnetism has had a direct impact on human history. Verschur (1993), for example, wrote that Columbus sailed by the compass; however, he sailed past the point where the magnetic and geographic poles were in the same direction. Beyond that point, magnetic north lay to the west of true north, not to the east.
Columbus’ ships, as a result, sailed further south than predicted. Had Columbus been sailing to the geographical west as he thought he was doing, he would have not sighted land within the time his crew had given for a landfall.
Magnetism, too, impacts on living things.
Many species are sensitive to magnetism, including honeybees, some migratory bird species, dolphins and whales. Verschur suggests that some whales may get stranded on beaches because of local irregularities in the Earth’s magnetic field, which points inland rather than out to sea at those locations. The effect of magnetism on humans is not well understood. Nevertheless, some applications of magnetism in human medicine are well established, such as magnetic resonance imaging
(MRI), a modern medical diagnostic tool. Some
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TEACHING PHYSICS have claimed that application of magnetic fields can heal various ailments (Biomagnetism 1996).
The purpose of this paper is to report what we know about conceptions of magnetic phenomena held by a number of groups.
Surprisingly, conceptions of magnetic phenomena
(Erikson 1994) have not been investigated as intensively as many other physical phenomena such as electricity and heat. Driver et al (1994) summarized those few studies they could find, and concluded: ‘approaches which draw on everyday experience and focus upon the uses of magnets would be advisable’.
Guth (1995) reported an in-depth investigation of two physics students’ understanding of electric and magnetic fields.
He noted that the concept of ‘field’ was little investigated. He reported that the two individuals’ thinking could be characterized as ‘concrete– symbolic’ or ‘formal’ modes.
6. What is a magnetic pole?
7. Do you think that the magnets some people put on their joints really work?
8. Is a big fridge magnet stronger than a small fridge magnet? Why or why not?
9. Does a magnet have to touch a metallic object to affect the object? Why or why not?
10. Do you think that magnets work on metallic objects only?
Each question was followed by about 10 cm of blank paper for the individual’s responses. The questions were derived from the results of the few studies of magnetism reported by Driver et al
(1994) together with questions we believe students might have asked themselves at some stage. Most participants took between 10 and 15 minutes to complete their responses.
Given the scarcity of research in this area, we decided to investigate the conceptions of four groups in the field of science education: 29 undergraduates in a primary program (PU), 15 in a secondary program (SU), 16 primary teachers
(PP) and 12 science undergraduates involved in a science tutoring program (ScU). These were convenience samples.
All of our volunteers were asked to write responses to ten questions designed to elicit their understanding of magnetism.
These questions were linked to three areas that (a) reflect views on magnetism as a phenomenon related to other scientific phenomena, (b) involve explanations of magnetic forces, and (c) have a practical focus on everyday uses of magnets. Participants were asked to write responses to each of the following ten questions:
1. Is there a link between magnetism and gravity?
2. Is there a link between magnetism and air?
3. Is there a link between magnetism and electricity?
4. How do you think magnetic attraction works?
5. How do you think magnetic repulsion works?
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Theme A. What is the relationship between magnetism and other phenomena?
This general focus included five questions that asked respondents to examine their ideas about the links between magnetism and other phenomena such as gravity, air and electricity, and probed concepts about field strength, and the exclusive attraction of magnets to metals.
Na¨ıve explanations were offered which generally included drawing a difference between the way the two functioned, while acknowledging that both were effects of some kind: ‘gravity is the Earth’s magnetism’; ‘gravity only operates downward, things can be drawn upward to a magnet’; and
‘with gravity objects are pulled to the Earth’s centre, with magnetism to the Earth’s poles’.
Many primary undergraduates saw commonalities in effect: of pulls, and of forces of attraction. Nearly half of these students gave an unexplained ‘yes’ answer, indicating perhaps difficulty with providing evidence for their ideas (compared to the majority of the secondary students who were more likely to propose some evidence or reason for their response). Some ideas separating the two concepts related to basic differences, such as gravity is the pull of the centre of the Earth, and magnetism is the due to the Earth’s poles; or gravity as a ‘pushing force’ and magnetism as a ‘pulling force’. Some students relied on their visualization of drawings or diagrams of the Earth, and

its magnetic field, and linked the two concepts, but without any explanation of how or why. One view was that both were linked because both have
‘something to do with the lumps of metal in the
Earth’. Other students seemed to view the two as one and the same thing: ‘Yes, because magnetism as a force attracts things and magnets have ‘north’ and ‘south’ poles. The land attracts things (people, plants, water etc) and this too has N and S poles’; and ‘Yes, gravity is the result of the magnetic pull between the Earth and the Moon’.
Secondary undergraduates gave some diverse conceptions about these two forces. Some argued for some similarity, in that both are forces that are attractive, and while they may not see them as
‘linked’, recognize commonalities in their effect
(push, pulls, fields) rather than their nature. Many stated differences such as: magnets for some objects, gravity for all objects, with one specifying metals only were attracted to magnets. None used a dipolar molecular description, although over half used terms related to ‘charge’ or ‘forces’, or ‘fields’. Views of the relative strengths were diverse: for one student gravity was stronger, for another, ‘electromagnetic fields’ were stronger.
One student made a link between the two as mathematical weighting of strength and distance.
(Of interest was the perseverance of the view that gravity is caused by the Earth’s spin.)
Magnetism was an inherent property of some objects and so did not need to be created, according to 5/29 PU and 4/15 SU. The use of electricity to produce magnetism was suggested by 4/15 SU and 1/29 PU; 2/15 SU indicated that stroking a metal object in one direction with a magnet could produce magnetism. The rest of the participants proposed alternative notions to explain how magnetism could be created. Generally, a magnetic pole was seen as being the end of the magnet (5/12 ScU, 3/16 PP).
It is unlikely that these groups would be able to draw out the essential differences in these two phenomena, and would be likely to preserve their own students’ misconceptions as they grapple with their own developing views.
Is there a link between magnetism and air?
The most frequent suggestion was that magnetism was different from air because magnetism is able to operate in a vacuum. However, many primary undergraduates suggested irrelevant distinctions, for example that magnetism is a force and air
TEACHING PHYSICS is an element, that the magnetic poles are not linked to air, that they may be linked because both are particles, and that since magnetism on
Earth occurs in the area with atmospheres, they must be interconnected.
Of this group, 8/29
PU gave responses that were ‘na¨ıve’; for the secondary group, the figure was 2/15.
None of the views of practising teachers or of the science undergraduates was classified in this way.
Two secondary responses suggested ways of distinguishing between the two forces that imply a very close causal connection between them based on isolated observation: that a magnet can suspend another magnet in the air so a force present in the air must hold the other magnet up, or that bar magnets with iron filings behave independently of air blown by an air conditioner. Those teachers who included an explanation generally chose an argument that magnetism operates in a vacuum, so it was independent of air.
Does a magnet have to touch a metallic object to affect the object?
A well represented view across all groups related to the idea of a ‘field’ extending past the visible limits of the magnet: the term ‘magnetic force field’ was used. Many participants specified that this was a force, that it had variable strength, that magnetic force operates at a distance, which particularly depended on the strength of the force.
Almost all participants from all categories accepted that magnets and magnetic objects did not have to be in contact for the object to be affected. For many, their explanation was related to the existence of a magnetic force field (4/16 PP,
1/12 ScU, 5/15 SU, 5/29 PU). Significantly, some of the participants appeared to visualize magnetic force as something tangible: something that was beamed out by the magnet and had to be strong enough to overcome things between the magnet and the object such as air so that it could affect the object. Perhaps there is the notion here of the force being ‘used up’ as it travels through space.
A significant group of participants believed that all metals were magnetic (9/29 PU, 6/15 SU,
7/12 ScU, 5/16 PP). Consistent with an ‘electricity’ model of magnetism, 3/29 PU claimed that carbon was also magnetic. A few participants recalled an experiment involving a magnetic ore since one PU and one PP accepted that not all metals were magnetic and some ores were. One other
PP claimed that only metals containing iron were magnetic.
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TEACHING PHYSICS
Do you think that magnets work on metallic objects only?
Overall, 44 per cent stated that magnets work on all metals. Relatively few (6%) stated that they only work on some metals.
A higher percentage (18%) were prepared to believe that non-metallic objects were also magnetic; reasons given included that ‘bauxite is magnetic’,
‘carbon and graphite are magnetic’, a very general
‘anything that contains positive and negative forces’ (one secondary response), radio waves and
‘electrically charged objects or solutions’.
In general, patterns of response for these five questions show that many primary undergraduates exhibited non-scientific notions about magnetism.
The notion that gravity is the Earth’s magnetism is a strong one for some of these students. Other interesting conceptions were that with gravity things are pulled to the Earth’s centre but with magnetism to the Earth’s poles, and that gravity operates downward only while things can be drawn upward to a magnet. An interesting na¨ıve notion proposed by a secondary undergraduate was that gravity was the result of the Earth’s spin. Even with those who saw the link between magnetism and gravity on the basis that they were both forces
(nine participants in all), their responses seem to indicate acceptance of the notion that gravity operates on the Earth only.
A relatively high minority of students from all categories either indicated that there was no link or made no comment. A significant proportion (16 participants in all) argued that magnetism could operate in a vacuum or was unaffected by air. However, two primary and two secondary undergraduates seemed to be concerned about the effect that particles in air could have on magnetism.
Theme B. How can magnetism be explained?
These questions related to the ways that participants chose to explain magnetism, what concepts or terms they employed, or what forces or particles they referred to in their explanations.
How do you think magnetic attraction works?
Many participants referred directly to an electrical model of attraction, invoking ideas of charges, movement of positive and negative ions, creation of aligned domains and movement of charged particles. Some responses were quite specific in using the concept of domains: for example, a secondary student wrote, ‘there are domains of
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Phys. Educ. 34(6) November 1999 positive and negative: attraction occurs by creating aligned domains’. The majority clearly supported a polar explanation of attraction, referred to
‘positive and negative poles placed together attract’, with a clear idea that magnets have a positive and a negative end, and that these different poles attract. Seven participants stated they had no explanation for magnetism, with an even distribution among the four groups.
How do you think magnetic repulsion works?
Responses to this question were generally similar to those for the previous question, indicating general support for a polar, or electrical positive and negative model. Interestingly, more references were made to the polar model for this question about repulsion than were mentioned for the question about attraction. Apparently, there was broad support for this idea when related to the context of repulsion. Na¨ıve explanations tended to focus on generalized particles causing repulsion, or of two fields pushing each other apart. Other descriptions (11%) involved an awareness of ‘like poles repel’, ‘similar poles repulse’ and ‘two of the poles on two magnets have field lines going the same way and push each other away’. The highest proportion of the responses (31 per cent) related clearly to unspecified positives and negatives, or charges, or to positive and negative ions, such as
‘two positives and two negatives’ and ‘the force of the ions in two like poles push them apart’. We cannot assume, however, that all participants who use the terms ‘positive and negative’ necessarily link these to electromagnetic charges, as they may be more limited terms referring to the usual symbols on magnets.
What is a magnetic pole? The most frequent response related to the positional factors at the
‘end of the magnet’, with some responses referring to the ‘point where the magnetic field begins’ or ‘the centre of the magnetic force’.
Other responses were in accord with an electrical model, for example ‘where all the charge is not met with another charge’, and ‘where atoms of magnetic force are strongest’.
One response suggested a pole was ‘the direction the magnet wants to point’.
Is there a link between magnetism and electricity?
Generally, participants were aware that electricity was used to generate magnetism,
‘electricity creates a magnetic field’, ‘magnetic properties are used in producing electricity’, or a simpler ‘they’re used to create each other’.

In fact, 38% gave responses that suggested the two phenomena ‘created each other’. Technical responses (13%) linked magnetism and electricity as movement of ions or electrons.
Overall, a relationship between electricity and magnetism in terms of ‘both having moving electrons or ions’ was frequently invoked. This notion of ions or electrons being involved with magnetism appears as a significant alternative.
Theme C. The application of magnets to everyday situations
This final section related to two questions, one asking whether the magnets some people put on their joints really work, and the other about whether a big fridge magnet is stronger than a small fridge magnet.
We anticipated that participants might have some experience of these in their daily lives.
Do you think that the magnets some people put on their joints really work?
Seventeen per cent attributed any success of magnets on joints to a placebo effect.
Notably, 10/15 SU made the greatest efforts to provide an explanation that might be considered ‘scientific’ for the efficacy of magnets; 28% of all respondents attempted such scientific explanations.
They suggested notions like ‘iron molecules’ in the blood, minerals like calcium and phosphorus in the body and electric pulses in the nervous system. Eighteen per cent cited personal experience of this effect.
Is a big fridge magnet stronger than a small
fridge magnet? Responses related the strength of magnetic force to surface area and to force, and to the way the magnet had been produced. Those
(42%) who accepted that a big fridge magnet was the stronger generally argued for a bigger surface area as the determining factor.
This implies a basic idea that the size of the magnet determines its strength.
Some responses suggested a more flexible interpretation—that size and strength were not directly linked. Four teachers argued that the small fridge magnet could be stronger depending on how it was magnetized: ‘it depends on how the electrons are aligned’, ‘depends on the material the magnet is made of’ and ‘depends on the number of positive and negative ions’.
TEACHING PHYSICS
Members of the secondary group were most likely to attempt to provide what they thought was a scientific explanation to a question.
Given that these students had completed or were about to complete a science degree, this is welcome.
Primary students were more likely to write down alternative conceptions; however, even some of the secondary group gave non-scientific explanations.
The most general model appeared to be an
electricity model of magnetism, in which the terms ion, electron or positive and negative are used to explain how attraction or repulsion works. The numbers in each group who held this model were: primary, 15; secondary, 7; science peer tutors, 7; teachers, 4.
There are different explanations for this widespread use of these terms and the associated notion of moving electrons or ions. Firstly, there is the possibility that participants conceptualize magnetism as having all the characteristics of electricity. Alternatively, participants might just be ‘loose’ in their use of technical language or they might understand, at a basic level, how attraction and repulsion work but lack the appropriate technical language to describe adequately their conceptions. Use of other terms such as ‘repulse’ and ‘detract’ provides further evidence for a lack of appropriate technical knowledge. Fourthly, if these participants are operating at a concrete rather than an abstract level of conceptualization then the objectification or mechanization of a process like
‘attraction’ into an object is aided by using objects or particles such as ions, electrons etc to explain this process. The role of language in science is of course crucial: see, for example, Sutton (1992).
The number of participants is small, and they are not necessarily representative. Nevertheless, given the paucity of our knowledge of conceptions of magnetism, the data reported here can help teachers in their planning of magnetism activities.
As we were writing this, Borges and Gilbert
(1998) reported conceptions of magnetism among various groups in Brazil, including secondary school students, technical school students, physics teachers, engineers and practitioners whose daily jobs are related to electricity and electromagnetism
(p 361). Their investigation led them to suggest five models of magnetism. These models, with
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TEACHING PHYSICS the number of respondents classified as holding this model, are as follows: magnetism as pulling
(8); magnetism as a cloud (8); magnetism as electricity (8); magnetism as electric polarization
(7); a field model (16). Another nine participants were classified as holding ‘mixed’ models.
A physicist who read this paper commented that most physics teachers will be aware of such misconceptions.
He further argued that unless students had been explicitly taught magnetism concepts, we should not expect them to understand these concepts.
All the students in the sample would have been taught magnetism in their high school years, because of the nature of the high school science curriculum.
More importantly, however, the physicist’s comment appears to undervalue the power of one of the most important learning principles: begin where students are.
To recognize student misconceptions, it is not sufficient to pay lip service to them: it means to seek actively to clarify what students know, to value it for its diversity, to demonstrate that as a teacher you value it for its potential as a tool to explain and predict phenomena, and then to restructure your lessons and the investigations you plan, to take account of students’ ideas. The term ‘misconceptions’ should not be a derogatory term; it is a term that should engage a teacher in reflection of the potential of students’ ideas and be a base from which these alternative ideas are honed, clarified and developed, not merely eradicated. Understanding what students know is not easy, often because their knowledge is tacit, difficult to verbalize and has not been reflected on before. Effective teachers actively use students’ alternative ideas, to replace the tradition of ‘one lesson’ with ‘multi-level lessons’ to support the multitude of ideas that students already have, which can hinder even the ‘best’ of teachers.
Effective teachers know that they must take students’ prior knowledge into account. This paper will help make effective teachers more effective in their teaching of magnetic phenomena.
Received 6 July 1998, in final form 21 May 1999
PII: S0031-9120(99)95592-2
Biomagnetism 1996 (Video no 6 in The Nature of
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