1. Three dimensional magnetic field model: A 8 x 11 x 8 cm hard acrylic unit is filled with a viscous fluid containing metal filings. It has a hollow center core so that a cylindrical magnet can be inserted from either end. Insert one magnet to illustrate the lines of magnetic force; Insert two magnets and then switch poles to graphically demonstrate attraction and repulsion. It can be put on overhead projector. 2. Two dimensional magnetic field model: a transparent acrylic case holds iron filings in a special viscous fluid. Shake the unit to distribute the filings evenly with the help of a glass rod that is sealed inside. Place the case on an overhead projector and a magnet under it. The filings will move to up along the lines of magnetic force.



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