This topic explores the key concepts of magnetism as they relate to:
- the phenomenon of magnetism
- magnetic forces and fields
- a theory of magnetism.
Key concepts of magnetism
- Magnets exert a force that can be described as a 'push' or a 'pull'.
- Magnets exert a force field that is called a 'magnetic field'. A magnetic field is a region in space around a magnet that will exert force on another magnet or magnetic material.
- Magnets attract materials composed of iron and nickel; these materials are described as being magnetic.
- Magnets vary in strength, size and shape.
- Magnets have north and south poles. The attracting power (magnetic field) of a magnet is greatest at its poles.
- Like poles of a magnet attract; unlike poles repel.
- Atoms are tiny constituents of matter and act like tiny magnets. In magnets and magnetic materials atoms form groups called 'domains', where their magnetic poles are aligned.
- In magnets, domains align themselves (north poles are in the same directions). In non-magnetic materials domains do not align themselves magnetically.
- Magnetic materials are made into temporary magnets by bringing them near a permanent magnet.
- Earth can be considered to be one large magnet.
- Temporary magnets can be made from a nail, wire and battery because an electric current produces magnetism.
Students' alternative conceptions of magnetism
Research into students' ideas about this topic has identified the following non-scientific conceptions:
- Poles are only at the ends of magnets.
- Big magnets are stronger than small magnets.
- Larger magnets are stronger than smaller magnets.
- The magnetic and geographic poles of Earth are located at the same place.
- The geographic and magnetic poles of Earth are identical.
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