Perform the following experiment: The purpose of this experiment is to use a compass to detect the weak magnetic field that exists around a current-carrying conductor. Breadboard a circuit consisting of a switch, a 12 V lamp, and 12 V dc power supply all connected in series.
1. With the switch open, position the compass on the top of and parallel with the conductor.
2. Briefly close the switch and watch the compass needle for any change.
3. Repeat with the compass positioned below the conductor.
4. Repeat with the polarity of the dc voltage source reversed.
a) In what general direction does the compass needle tend to move to position itself when current flows through the conductor?
b) How does the direction of the compass needle movement compare when the compass is placed on top and beneath the conductor?
c) How does the direction of the compass needle movement compare when the polarity of the dc voltage source is reversed?