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 do the lines along which the iron fillings align represent?

Options

A. North pole and south pole of the magnet
B. Strength of the magnet
C. Magnetic field lines
D. Gravitational force

Explanation

To solve the question regarding the arrangement of iron filings around a bar magnet, we can break it down into the following steps:

### 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 filings align themselves in a specific pattern.

2. **Observation of Iron Filings**:
- After tapping the board, the iron filings will arrange themselves in a pattern that reflects the influence of the magnetic field created by the bar magnet.

3. **Magnetic Field Representation**:
- The lines along which the iron filings align represent the magnetic field lines of the bar magnet. These lines illustrate the direction and strength of the magnetic field around the magnet.

4. **Characteristics of Magnetic Field Lines**:
- The density of the lines indicates the strength of the magnetic field: where the lines are closer together, the magnetic field is stronger, and where they are further apart, the magnetic field is weaker.
- The lines emerge from the north pole of the magnet and enter the south pole, forming closed loops.

5. **Conclusion**:
- Therefore, the lines along which the iron filings align represent the magnetic field lines of the magnet, showing the direction and strength of the magnetic field around it.

### Final Answer:
The lines along which the iron filings align represent the magnetic field lines of the bar magnet.

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