A student fixes a sheet of white paper on a drawing board. He places a bar magnet in the centre of it. He sprinkles some iron filings uniformly around the bar magnet. Then he taps the board gently and observes that the iron filings arrange themselves in particular pattern.
What does the crowding of iron filings at the end of the magnet indicate?

Options

A. Magnetic field is strongest near the poles of the magnet.
B. Magnetic field is weakest near the poles of the magnet.
C. There is no significant magnetic field at the poles of the magnet.
D. The significance of polarity

Explanation

### Step-by-Step Solution:

1. **Understanding the Experiment**: The student places a bar magnet at the center of a sheet of paper and sprinkles iron filings around it. When the board is tapped, the iron filings align themselves in a specific pattern.

2. **Observation of Iron Filings**: After tapping the board, the iron filings gather more densely at the ends of the bar magnet. This indicates a variation in the magnetic field strength around the magnet.

3. **Magnetic Field Concept**: A magnet creates a magnetic field around itself. This field can be visualized using magnetic field lines, which represent the direction and strength of the magnetic field.

4. **Magnetic Poles**: The bar magnet has two poles: the North Pole and the South Pole. The magnetic field lines emanate from the North Pole and enter the South Pole.

5. **Crowding of Iron Filings**: The crowding of iron filings at the ends of the magnet indicates that the magnetic field is stronger at these points. The density of the iron filings represents the strength of the magnetic field; more filings mean a stronger magnetic field.

6. **Conclusion**: Therefore, the crowding of iron filings at the ends of the magnet indicates that the magnetic field is strongest near the poles of the magnet.

### Final Answer:
The crowding of iron filings at the ends of the magnet indicates that the magnetic field is strongest near the poles of the magnet.

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