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| Magnetic Fields and Field Lines |
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| If a small compass needle is placed at a point near the north pole of a bar magnet, the needle turns round on its pivot and settles in a fixed direction as shown in figure. |
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| At other points away from the pole the needle settles tangent to the field lines shown. The magnet exerts a magnetic force in this area and the region round the magnet is called 'magnetic field'. By plotting the directions indicated by the compass needle at various points in this region, the magnetic field an be mapped out on a sheet of paper. |
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| It should be noted that no two-field
lines cross each other. A line of force can be defined as a line, tangent to
which at any point gives the direction of the magnetic field at that point.
These field lines originate at the north pole and terminate at the south
pole. |
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| We can also demonstrate the magnetic field by sprinkling iron filings on a sheet of paper laid on magnets and tapping the paper lightly. The iron filings get converted into small magnets by induction. They settle themselves along the lines of force in the magnetic field forming different patterns as shown in figure. |
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