What Makes A Thing Magnetic?

Many magnets are made of steel, which is iron plus some other things. Iron and steel are made up of many magnetic domains. Each domain is a very small area with billions of atoms. In an ordinary scissor blade, these domains face in different directions.

We would say:

  • The domains are unaligned.
  • The scissor blade does not have a magnetic field.
  • It will not attract magnetic objects.
One way to change the steel into a magnet is to stroke the scissor blade with a magnet. When you do this, the domains change and the scissor blade starts to develop a magnetic field of its own! In the drawing above, find a domain that already faces north. Now look below. What happened to that domain? Now look at another domain that faces some other direction. How did it change? Below is what happens inside the scissor blade when it becomes slightly magnetized.
   

We would say:
  • The domains are partly aligned.
  • The scissor blade has a weak magnetic field.
  • The scissor blade is a weak magnet.
  • It will pick up iron bits and other objects of small mass.

As these north-facing domains grow larger, the scissor blade becomes a still stronger magnet!

   

We would say:
  • The domains are mostly aligned.
  • The scissor blade has a strong magnetic field.
  • The scissor blade is a strong magnet.
  • It will pick up more massive objects.

Try this experiment at home and impress your friends and family!