Download 1] How will you show the directive property of a magnet? Suspend a

Science -Magnetism
STD 6
1] How will you show the directive property of a magnet?
Suspend a bar magnet freely .Note the direction in which it comes to rest. It always comes to
rest along the north- south direction of the earth. This is termed as the directive property of a
magnet.
2] Uses of a magnet:
1] Electric motors and generators rely on magnets.
2] Magnets are often used in toys.
3] Magnets are used in scrap and salvage operations.
4] TVs and computer screens employ electromagnets.
5] Speakers and microphones use permanent magnets.
6] Hard disks record data on a thin magnetic coating.
3] Properties of magnetic lines of force:
1] Each line is a closed and continuous curve.
2] They originate from the north pole of the magnet and terminate at the South Pole.
3] They never intersect each other.
4] They are crowded near the poles where the magnetic field is strong.
5] They affect the magnetic compass needle.
4] How will you test whether a given rod is a magnet or not?
Bring the given rod near some magnetic substances like iron, cobalt or nickel. If these are
attracted to the given rod, then it is a magnet.
5] Difference between a magnet and soft iron:
Magnet
1) Have a higher carbon content
2) These are permanent magnets
Soft iron
1) Have a lower carbon content
2) Used to make electromagnets
3) Retain their magnetic properties for a
very long time.
3) Can be effectively magnetised and
de-magnetised.
6] How can a bar magnet be used to know the north-south direction of a place?
Suspend a bar magnet freely. Note the direction in which it comes to rest. The north pole of
the magnet will always point towards the north pole of the earth, while the south pole of the
magnet will point towards the south pole of the earth.
7] Define:
A] A magnetic compass: It is a small magnetic needle pivoted at the centre of a brass box
having a glass top. The needle is free to move about its centre. The end of the needle, which
indicates its north pole, is painted red.
B] Magnetic field: The space around the magnet where its influence can be experienced is
known as the magnetic field.
C] Magnetic lines: These are curved lines used to represent the magnetic field.
D] Earth’s magnet: The earth may be assumed to have a big magnet buried deep inside it,
with its axis at about 19 to the geographic axis. The north pole of this magnet is closer to the
geographic South Pole and the South Pole is closer to the geographic North Pole. The earth’s
magnet has its own magnetic field.
8]
Uses of the magnetic compass:
1] To locate the direction of a place.
2] Used by sailors and navigators to find direction when they sail to unknown locations.
9] Will a magnetic compass needle placed near a bar magnet, rest in the n-s direction?
Explain.
No, a magnetic compass needle placed near a bar magnet will not rest in the n-s direction as it
is under the influence of the magnetic field of the bar magnet.
10] How will you use a bar magnet and some iron filings to obtain the magnetic lines?
Spread some iron filings evenly on a white sheet of paper. Place a bar magnet below the
paper. Now gently tap the paper. The iron filings experience a force due to the magnet and
hence align in a particular pattern, depicting the magnetic lines of force.
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