Edexcel IGCSE Physics 复习笔记 6.1.1 Magnetism

Poles of a Magnet

• The ends of a magnet are called poles
• Magnets have two poles: a north and a south

Poles of a Magnet

The Law of Magnetism

• When two magnets are held close together, there will be an attractive or repulsive force between the magnets depending on how they are arranged:

• • Two like poles (S and S or N and N) repel each other
  • Two unlike poles (S and N) attract each otherThe Law of Magnetism states that:
• The attraction or repulsion between two magnetic poles is an example of a non-contact force

• Magnetic materials can be soft or hard
• • Are easy to magnetise
  • Easily lose their magnetism (temporarily magnetised)Magnetically soft materials (e.g. iron):
• • Are difficult to magnetise
  • Do not easily lose their magnetism (permanently magnetised)Magnetically hard materials (e.g. steel):
• Permanent magnets are made out of magnetically hard materials
• • This means that electromagnets can be made magnetic or non-magnetic as an when requiredElectromagnets are made out of magnetically soft materials