The galvanometer is an instrument for measuring small electric currents by the deflection of a moving coil. In this experiment, we will make a galvanometer and determine if an electric current affects a magnet.
Things Required:
Aluminium foil, 1 yd. (1 m)
Compass
Cardboard box to fit the compass
Scissors
D-cell battery
Directions:
Cut a piece of aluminium about 36 inches × 24 inches (100 cm × 60 cm). Fold the aluminium piece in half lengthwise five times to form a thin strip 36 inches (100 cm) long.
Place the compass in the box. Wrap the aluminium strip around the box as many times as possible, leaving about 6 inches (15 cm) free on both ends of the strip. Turn the box with the compass so that the aluminium winding may point in a north-to-south direction. Tape one end of the aluminium strip to the positive end of the battery.
Watch the compass needle as you touch the free end of the metal strip to the negative end of the battery. Alternately, touch the metal strip to the battery and remove it several times.
This Is What Happens:
The needle on the compass moves away from, and then returns to, its north-to-south direction when the metal strip is touched to and then removed from the battery.
Science Behind It:
Electrons flow out of the battery, through the aluminium strip, and back to the battery. Moving electrons produce a magnetic field. Since the aluminium strip is turned in a north-to-south direction, the movement of electrons through the strip produces a magnetic field pointing east and west. The needle of the compass will be pulled towards this magnetic field, thus indicating that an electric current is flowing through the strip. The larger the current through the strip, the stronger the magnetic field that is produced.
