Q. Why does a compass needle always get aligned in the north-south direction?
Ans. The particular alignment of the compass needle is attributed to the interaction between two magnets. All magnets have two poles, a north pole and a south pole, and the north pole of one magnet is attracted to the south pole of another magnet and vice-versa. Actually, the compass needle itself is a little magnet with two magnetic poles and the earth acts as a really big magnet due to the magnetic field created by its iron core. The Earth's magnetic south pole lies near to its geographic north and the magnetic south pole near its geographic south. So the compass needle when allowed to spin whichever way it wants, will always line itself along the north-south direction.