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Pointer: Does an Electric Current Affect a Compass? (page 2)

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Author: Janice VanCleave

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    1. Since an electric current produces a magnetic field, could an electric current be used to magnetize a needle? Measure and cut a 3/4-inch × 3/4-inch (l.9-cm × 1.9-cm) piece of cardboard, and ask an adult to insert a nonmagnetic needle through the cardboard square. Place the cardboard and needle in the center of a 12-inch (30-cm) foil strip, with the needle laying perpendicular to the strip. Lay the strip on a wooden table, and stand the battery on one end of the strip. Fold the strip over the needle and hold its ends against the ends of the battery for five seconds. Determine if the needle has been magnetized by placing the cardboard square in a bowl of water. Use a compass to verify that the needle floats in a north to south direction and returns to this position if rotated.
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    3. Would winding the foil around the needle more times affect the magnetic strength of the needle? Use a 24-inch (60-cm) foil strip. Make three loops in the foil. Place a second square of cardboard with an unmagnetized needle inside the coil. Then, repeat the previous experiment. Compare the strength of the magnetized needles by turning them in an east-to-west position and observing the time it takes for them to return to a north-to-south position.
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    5. Experiment further by using 18-gauge or smaller wire instead of the aluminum foil. Display models of each instrument, indicating the strength of the magnets produced.
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