When a bar magnet is placed in iron filings, the filings arrange themselves in lines called magnetic field lines. These lines represent the magnetic field produced by the magnet and indicate the direction of the field from the south to north pole in closed curves. No two field lines cross. The strength of the magnetic field increases with increasing current in a wire. A solenoid, which is a coil of insulated copper wire wrapped into a cylinder shape, produces a strong magnetic field inside that can magnetize iron placed within it, creating an electromagnet.

1. PHYSICS

2.  When a bar magnet is kept in middle of iron
filings, the iron filings arrange themselves in a
pattern.
 The region surrounding the magnet, in which
the force of the magnet can be detected, is said
to have a magnetic field.
 The lines in which the iron filings align
themselves is called magnetic field lines.

4.  The direction of field lines is from south pole
to north pole. Thus magnetic field lines are
closed curves.
 No two field lines are found to cross each
other. If they did, it would mean that at the
point of intersection, the compass would point
towards 2 directions, which is not possible.

6.  The magnitude of magnetic field increases as
the current in the wire increases.
 In pg 226, activity 13.5

7. ??????????
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11.  A coil of many circular turns of insulated
copper wire wrapped closely in the shape of a
cylinder is called a solenoid.
 A strong magnetic field produced inside a
solenoid can be used to magnetize a piece of
magnetic material , like a piece of soft iron,
when placed inside a coil. The magnet so
formed is called electro magnet.

18. DONE BY

20. ONE OF THE
MEMBER OF the