Chapter 21: MAGNETISM
magnets have two poles, north seeking end or North Pole
and south seeking end or South Pole.
– Materials attracted towards a magnet [iron,
magnetic – Materials that are not attracted towards
freely suspended bar magnet always rests in the North
a rectangular piece of iron. Place it on the table. Now
take a bar magnet and place one ofits poles near one edge
of the bar of iron. Without lifting the bar magnet, move
it along the length of the iron bar till you reach the
other end. Now,lift the magnet and bring the pole (the
same pole you started with) to the same point of the iron
bar from which you began. Move the magnet again along
theiron bar in the same direction as you did before. Repeating these
several caused the iron bar to become a magnet.
magnetism, similar poles repel and opposite poles attract
can be lost by heating, hammering or dropping magnet
from a height.
force can be attractive or repulsive but gravitational
force is always attractive.
force is stronger than gravitational force.
force is 100 times stronger than EM force but range is
force doesn’t need an intervening medium.
field produced by a current in a conductor decreases as the
distance from it increases.
hand thumb rule gives the direction of magnetic field
due to current in a conductor. Thumb points in the
direction of current and curled fingers point in direction
of magnetic field.
field is produced even by the weak electrical impulses of
our nerve cells. Significant magnetic field is present in
brain and heart. The magnetic field produced by the body
is the basis of MRI scans that get images of body parts.
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