December 18, 2011

6.5 Magnetic materials

Understand that magnetism is induced in some materials when they are placed in a magnetic field.

  1. Stroke a magnet along a steel bar and an iron bar
  2. Try picking up some bar clips
  3. Bang both bars on the desk
  4. Now try picking up the paperclips again

Through this experiment we have magnetised the steel and iron bars so that we can pick up lightweight magnetic objects.

Tap the magnetised bars onto a table gently and try to pick up the paperclip again. What you should notice is that the steel retains some of its magnetism and can pick up the paperclip but the iron bar loses its magnetism completely. This is because steel is magnetically hard.

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