Thursday, December 11, 2008

Physics: Making Magnets

Last week the kids discovered that iron-containing metals can themselves becomes magnets if they are rubbed by a magnet. We used this observation to build compasses in 3 easy steps:
  • Rub a light-weight iron needle with a magnet 50 or so times.
  • Stick it through a thin piece of Styrofoam.
  • Set the whole business afloat in a bowl of water and observe how, try as you might, you cannot prevent the needle from pointing along a north-south axis.
Afterward, the kids built electromagnets. It turns out in an electric circuit, the movement of electrons creates a magnetic field. Because it is quite weak, you might not notice it. One way to increase it's strength is by building a circuit with MANY loops of wire, with each loop reinforcing the strength of the magnetic field. In our case, the kids wrapped wire around an iron nail. The kids explored the effects of changing the number of loops on the strength of the electromagnet.

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