KNOWLEDGE IN MAGNETS-PART 2
KNOWLEDGE IN MAGNETS-PART 2
Take
a bar magnet. Put a mark on one of its ends for identification. Now, tie
a thread at the middle of the magnet so that you may suspend it
from a wooden stand.
Make
sure that the magnet can rotate freely. Let it come to rest.
Mark
two points on the ground to show the position of the ends of
the magnet
Draw
a line joining the two points. This line shows the direction in which
the magnet
was
pointing in its position of rest.
Now, rotate
the magnet by gently pushing one end in any direction and let it come
to rest.
Again,
mark the position of the two ends in its position of rest. Does the
magnet
now point in a different direction?
Rotate
the magnet in other directions and note the final direction in which
it comes to rest.
Do
you find that the magnet always comes to rest in the same
direction? Now can you guess the mystery behind the statue in the
Emperor's chariot?
Repeat
this activity with an iron bar and a plastic or a wooden scale
instead of a magnet.
Do
not use light objects for this activity and avoid doing it
where there are currents of air.
We
find that a freely suspended bar magnet always comes to rest in
a particular direction, which is the North-South direction.
Use
the direction of the rising sun in the morning to find out the rough
direction towards east, where you are doing this experiment.
If
you stand facing east, to your left will be North.
Using
the Sun for finding directions may not be very exact, but, it will
help to make out the direction North from the South, on your line.
Using
this you can figure out which end of the magnet is pointing to the North
and
which points to the South.
The
end of the magnet that points towards North is called its North seeking
end or the North pole of the magnet.
The other
end that points towards the South is called South seeking end or the South
pole
of the magnet. All magnets have two poles whatever their shape may
be.
Usually,
north (N) and south (S) poles are marked on the magnets.
For
centuries, travelers have been making use of this property of magnets
to find directions.
It
is said that in olden days, travelers used to find directions by
suspending natural
magnets
with a thread, which they always carried with them.
Later
on, a device was developed based on this property of magnets. It is
known
as the compass.
A
magnetized needle is pivoted inside the box, which can rotate freely with
directions marked on it.
The compass
is kept at the place where we wish to know the directions. Its
needle indicates the north-south direction when it comes to rest.
The
compass is then rotated until the north and south marked on the dial
are at the two ends of the needle.
To
identify the north-pole of the magnetic needle, it is usually
painted
in a different color.
CAN WE MAKE OUR OWN
MAGNET???
There
are several methods of making magnets. Let us learn the simplest one.
Take
a rectangular piece of iron. Place it on the table.
Now
take a bar magnet and place one of its 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 the iron bar in the same direction as you did
before.
Repeat
this process about 30-40 times.
Bring
a pin or some iron filings near the iron bar to check whether it has
become a magnet.
If
not, continue the process for some more time. Remember that the pole
of the magnet and the direction of its movement should not change.
You
can also use an iron nail, a needle or a blade and convert them into
a magnet.
I
think now you know how to make a magnet.
WOULD YOU LIKE TO MAKE YOUR
OWN COMPASS???
Magnetize
an iron needle using a bar magnet.
Now,
insert the magnetized needle through a small piece of cork
or foam.
Let
the cork float in water in a bowl or a tub. Make sure, that the
needle does not touch the water.
Now
Your compass is ready to work.
Take
a note in which direction the needle points when the cork
is floating.
Rotate
the cork in different directions, with the needle which is fixed in
it, .
Note the
direction in which the needle points when the cork begins to float
again without the needle always point in the same direction, when
the cork stops rotating?
PRECAUTIONS:
Magnets
lose their properties if they are heated, hammered or dropped
from some height.
Also,
magnets become weak if they are not stored properly.
To
keep them safe, bar magnets should be kept in pairs with their unlike
poles on the same side.
They
must be separated by a piece of wood while two pieces of soft iron
should be
placed
across their ends.
For
horse-shoe magnet, one should keep a piece of iron across the poles.
Should
keep magnets away from cassettes, mobiles, television, music
system, compact disks (CD's) and the computer.
***PART 1 LINK***
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