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Tracing the magnetic field:
This activity requires a small compass needle, white paper, a drawing board, board pins, or cello tape.
The magnetic field can be traced using a compass needle by following the given steps.
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Experimental set-up
  1. A white sheet of paper is secured on the drawing board with board pins or cello tape.
  2. At the edge of the paper, a small plotting compass needle is placed.
  3. The board is rotated until the edge of the paper is positioned parallel to the magnetic needle.
  4. The needle is then kept at the centre of the paper.
  5. The ends of the needle are marked when they come to rest with their new north and south pole positions.
  6. A straight line representing the magnetic meridian is formed when these points are joined.
  7. At the paper's corner, the cardinal directions such as \(N-E-S-W\) are drawn.
  8. The bar magnet is then kept on the line drawn at the middle of the paper keeping its north pole facing the Earth's geographic north.
  9. Now, the bar magnet's outline is sketched.
  10. The plotting compass is positioned near the bar magnet's north pole, and the needle's end (north pole) is labelled \(A\).
  11. Now, the compass is moved to a new position such that the south pole occupies the position of the north pole.
  12. By this method, the compass is placed near the south pole of the magnet, one step at a time. \(B\), \(C\), \(D\), \(E\), \(F\), \(G\), \(H\), and \(I\) are the deflecting points.
  13. A curvy line representing the magnetic lines of force is then drawn by joining the plotted points around the magnet.
Likewise, several magnetic lines of force are drawn around the magnet. These lines represent the magnetic field of a magnet. The arrows heads represent the direction of the lines.
Magnetic filed of a magnet
When the compass needle is kept closer to the magnet, it gets deflected to a larger extent. The deflection of the needle steadily decreases as the distance increases. There is no magnetic deflection at one point because there is no magnetic force at that location.
This demonstrates that each magnet has a magnetic effect in its field or region.