CG Board Class 6 Science Magnetism Notes / Textbook Exercises / Question Answers as well as Additional Question Answers from the Chapter.
Discovery of the Magnet:
A shepherd named Magnus discovered magnets around 2000 years ago in a village in Asia Minor.
He found black stones (iron ore) with the ability to attract iron attached to his iron-tipped stick near a waterfall.
Natural Magnets:
Natural magnets, like magnetite (iron ore), exist in nature but are not very powerful.
They have irregular shapes, are less stable, and fragile, making them less practical for most purposes.
Artificial Magnets:
Powerful artificial magnets are made from materials like steel, cobalt-steel, nickel-steel, or aluminum-nickel-cobalt alloy (Alnico).They are more stable and widely used in various shapes and sizes.
Types of Artificial Magnets:
Bar Magnet (Rod Magnet): Shaped like cuboids or cylinders.
Horse-shoe Shaped Magnet: Bar magnets bent in the shape of a horseshoe.
U-shaped Magnet: Formed by bending rod magnets into a U-shape.
Spherical Magnet: A long rod with spheres at its ends.
Magnetic Needle: Flat, thin steel pieces with a central pivot to move freely horizontally.
Magnetic Compass: Magnetic needles in boxes with transparent plates used for navigation.
Magnetic vs. Non-Magnetic Substances:
Magnetic Substances: Attracted by magnets and can be turned into magnets. Examples include iron, cobalt, nickel, and their alloys.
Non-Magnetic Substances: Not attracted by magnets and cannot be magnetized. Examples include copper, aluminum, sulfur, carbon, and more.
Atomic Nature of Magnets:
Cutting a bar magnet into pieces does not separate the poles; each piece still has a north and south pole.
This implies that the smallest particle of a magnet, an atom, has a complete magnetic nature.
Magnetic Protection:
To protect a magnet’s magnetic properties, a rod of soft iron is placed on the poles of a horseshoe magnet.
Bar magnets are stored with their dissimilar poles near each other and soft iron bands to prevent loss of magnetism.
Earth as a Magnet:
Earth itself acts as a magnet with a magnetic north near its geographical south and vice versa.
A freely suspended magnet’s north pole points to the geographical north.
Iron buried in the Earth can become a magnet, with the end pointing towards the geographical north becoming its north pole.
Use of Magnets:
Magnets have various uses in daily life, including in bulletin boards, toys, electric devices (bells, generators, televisions), medical procedures, and for extracting iron from ores.
The magnetic compass, crucial for navigation in aircraft and ships, is one of the most important applications.
Magnets are also used in cranes to lift heavy iron blocks.
