Question

Four identical iron bars were dipped in a heap of iron filings one by one. The figure shows the number of iron filings sticking to each of them. Which of the iron bars is not a magnet? Justify your answer.

(a) (b) (c) Fig. \( 13.5 \) (d)

Answer 1

Step 1: Properties of magnet

1. When a magnet is dipped in iron filings, we can observe that the iron filings cling to the end of the magnet as the attraction is maximum at the ends of the magnet. These ends are known as poles of the magnets.
2. Magnetic poles always exist in pairs.
3. Whenever a magnet is suspended freely in mid-air, it always points towards north-south direction. Pole pointing towards geographic north is known as the North Pole and the pole pointing towards geographic south is known as the South Pole.
4. Like poles repel one other, but unlike poles attract each other.
5. The magnetic force between the two magnets is greater when the distance between these magnets are lesser.

Step 2: Analyzing the given figure

As it is clearly visible that iron bar (b) doesn't attract any iron fillings.

Hence, iron bar (b) is not the magnet.