Magnets and Magnetic Materials
Section: Physics | Syllabus: Cambridge Primary Stage 5 Science (0097)
Magnets and Magnetic Materials
- A magnet can attract magnetic materials, and can attract or repel another magnet.
- A magnetic material is attracted to a magnet but is not necessarily a magnet itself.
- Repulsion is the clearest test that both objects are magnets - a magnetic material that is not a magnet can only ever be attracted, never repelled.
- Iron and steel are common magnetic materials; plastic, wood, glass and most other metals (such as aluminium and copper) are not.
Forces Acting over a Distance
- Magnetic forces act even when objects are not touching - this is called a non-contact force.
- Every magnet has two poles: unlike poles (north and south) attract, while like poles (north and north, or south and south) repel.
- A magnet attracts a magnetic material whichever pole is brought near it, because the material itself does not have fixed poles.
- The strength of the magnetic force usually becomes weaker as the distance between the objects increases.
Unlike poles attract; like poles repel
Magnetic Strength
- Magnets can have different strengths, even if they are a similar size or shape.
- Strength can be compared by measuring a pulling force, the mass of an object lifted, or the number of identical objects (such as paperclips) attracted.
- For a fair comparison, keep the object being attracted, the distance and the method the same each time.
- Repeat measurements to improve reliability.
Question: Block P repels block Q. Block R is attracted to P but never repels it. What can you conclude? [2]
Repulsion can occur only between two magnets. Attraction alone could mean the object is a magnet or a magnetic material. AnswerP and Q are magnets. R is magnetic, but the evidence does not prove that it is a magnet.
Common Mistakes
MistakeIf an object is attracted to a magnet, it must be another magnet.
FixMagnetic materials are also attracted. Repulsion proves that both objects are magnets.
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