A long rod made of soft iron is fixed in a vertical position. If a strong magnet A is brought into contact with its upper end, as shown in Fig., then the rod becomes so strongly magnetised that its lower end can support several small objects. If the same magnet is brought in contact with the side of the rod, quite close to the lower end (Fig,), then there is no such strong magnetisation, and the same objects cannot be supported at the lower end of the rod. Explain why magnet A acts differently in the two cases.