- A galvanometer is used to indicate electric currents. In this lab you will construct a galvanometer and test it.
MATERIALS NEEDED:1-meter length of lacquered bell wire
Compass
Cardboard to make box around compass
Scissors
Ruler
Pencil
Tape
Emery board
D-cell batteryPROCEDURE:
Using the cardboard, scissors, ruler, pencil, and tape, construct a box to house the compass. It needs to be slightly higher than the thickness of the compass. If the compass came in a box its size, that is even better.
Place the compass in the box. Wrap the wire around the box as many times as possible, in the north south direction of the compass, leaving about 15 cm free on both ends.
Using the emery board, sand off the lacquer coating from both free ends of the wire, about 2 cm from each end.
Turn the compass on the table so that the needle is pointing north, in line with the wrapped wire.Tape one end of the wire to the positive end of the D-cell battery.Watch the compass needle as you touch the free end of the wire to the negative end of the battery. Touch and remove the wire to the battery several times, watching the compass needle.DISCUSSION:
- The needle on the compass moves away from the north position when the wire is touched to the battery, and returns when the wire is removed from the battery. Electrons flow out of the battery, through the wire, and back to the battery. Moving electrons produce a magnetic field. Because the wire is wrapped in a north-to -south direction, the magnetic field that is produced is pointing east and west. The needle of the compass will be pulled toward this magnetic field, indicating that an electric current is flowing through the strip. The larger the current through the wire coil, the stronger the magnetic field that is produced.
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- The needle on the compass moves away from the north position when the wire is touched to the battery, and returns when the wire is removed from the battery. Electrons flow out of the battery, through the wire, and back to the battery. Moving electrons produce a magnetic field. Because the wire is wrapped in a north-to -south direction, the magnetic field that is produced is pointing east and west. The needle of the compass will be pulled toward this magnetic field, indicating that an electric current is flowing through the strip. The larger the current through the wire coil, the stronger the magnetic field that is produced.
CONSTRUCTING A
GALVANOMETER
INTRODUCTION: