Q1.
When the needle comes to rest, your magnetic compass is ready for use. Note the direction in which either side of the needle points. Rotate the cork gently and wait till it stops rotating. Repeat this a few more times. Do the ends of the needle always point in the same direction?
Answer
Yes. However many times you spin the cork, the needle swings a little and then settles with the same end pointing north and the other end pointing south, every single time.
Spin 1 → needle rests along north-south
Spin 2 → same ends, same directions
Spin 3 → same again
The magnetised needle is behaving exactly like a freely suspended bar magnet.
Spin 2 → same ends, same directions
Spin 3 → same again
The magnetised needle is behaving exactly like a freely suspended bar magnet.
Why the cork and water are needed: the needle must be free to turn with almost no friction. Floating on water lets it swing easily in the horizontal plane, and the Earth's magnetism then does the rest. Notice that the needle also stays horizontal because it is balanced through the cork.
Check it yourself: Bring a steel scissors close to your floating compass. The needle swings away from north. Take the scissors away and it returns. That is why a compass must be read away from iron objects.