AIM OF THE EXPERIMENT: To find out how metals affect a magnetic field.MATERIALS: four small metal paper clips, aluminium foil, a rectangular magnet, a steel spatula. METHOD: Put the paper clips on the table, cover them with a sheet of foil and place the magnet on top.
Lift the magnet and see whether the paper clips have moved.
Put the paper clips under the spatula.
Place the magnet on the spatula.
Lift the spatula with the magnet and see whether the paper clips have moved.
RESULTS: The magnet attracts the paper clips through the foil, but not through the spatula.
WHY? A magnetic field can pass through aluminium, but a steel blade limits its action. The blade of the spatula is attracted to the magnet, and the metal the blade is made of draws the magnetic field into itself, as it were. As a result the steel blade becomes a barrier that limits the spread of the magnetic field.