XO - Electricity and magnetism

Required
XO laptop
75mm (3 inch) nail
insulated copper wire
3.5 mm phono plug
refrigerator magnet

Method
Wrap 50 turns of insulated wire onto a nail and connect the two ends to a phono plug as shown (if it is a stereo plug, probably the red wire and the copper shield). Connect the phono plug to the microphone input.


Start the Measure activity, sound tab, time base, maximum vertical sensitivity, minimum sweep speed (as shown).


Wipe the sharp end rapidly over the back of the fridge magnet, try both directions.


Questions
Try a different number of turns of wire
Try moving the nail more slowly, what happens to the period, frequency and amplitude of the wave?
What is happening?
Why does it work better on one axis of the magnet? (hint rub 2 magnets together)