Bar magnet alignment explanation:

Bar magnets always show North to South alignment due to the fundamental property of magnets called magnetic field lines.

Magnetic field lines:
- Magnetic field lines are imaginary lines that represent the direction and strength of the magnetic field around a magnet.
- These lines flow from the North pole to the South pole outside the magnet and from the South pole to the North pole inside the magnet.

North to South alignment:
- When a bar magnet is freely suspended, it aligns itself in a North to South direction due to the Earth's magnetic field.
- The Earth itself acts as a huge magnet with its North pole located near the geographic South pole and its South pole near the geographic North pole.
- Since opposite poles attract each other according to the magnetic field lines, the North pole of the bar magnet points towards the Earth's geographic North pole (magnetic South pole), and the South pole of the bar magnet points towards the Earth's geographic South pole (magnetic North pole).

Stability of alignment:
- The North to South alignment of a bar magnet is stable because any attempt to rotate it would result in an increased magnetic potential energy, making it return to its original alignment.

In conclusion, the North to South alignment of a bar magnet is a result of the magnetic field lines and the interaction with the Earth's magnetic field, ensuring stability in its orientation.