Curriculum
Science — First Preparatory
Unit 1: Matter
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Unit 2: Forces
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Unit 3: Life
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Unit 4: Earth and Space
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Text lesson
Magnetic Forces
Magnetic Forces
Magnetising materials and removing magnetism
Magnetising materials and removing magnetism
- A magnetic material such as iron can be magnetised by induction.
- If we bring a strong magnet near it, or stroke it with a bar magnet in one direction several times, its magnetic regions line up in one direction.
- It then becomes a temporary or permanent magnet, depending on the material.
- Magnetising by stroking with a magnet, or by placing an iron core inside a coil that carries an electric current.
- Demagnetising by strong heating, by repeated hammering, or by dropping the magnet hard. This scatters the magnetic regions and weakens the magnetism.
- An electromagnet is a coil of insulated wire wrapped around an iron core.
- Its strength increases when the current increases and when the number of turns in the coil increases.
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