Fun with Magnets

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Short Answers:

Q 1. What happened to a magnet when it is cut into two pieces ?

Ans: When a magnet is cut into two pieces, each piece becomes a smaller magnet with its own north             and south poles. 

Q 2. What are the soft and hard magnetic materials ?

Ans: Soft Magnetic Materials: These materials are easily magnetized and demagnetized. Examples             include:

  1. Iron
  2. Nickel-iron alloys

        Hard Magnetic Materials: These materials retain their magnetism once magnetized. Examples            include:

  1. Ferrites
  2. Alnico (Aluminum-Nickel-Cobalt)
Q 3. Why does a bar magnet always point in north -south direction ?
Ans: A bar magnet always points in the north-south direction because Earth's magnetic field exerts a force on it. The magnet aligns itself with Earth's magnetic field, with its north pole pointing towards Earth's magnetic south pole (geographic north) and its south pole towards Earth's magnetic north pole (geographic south).

Q 4. Can the north pole and south pole of a magnet be separated ?
Ans: No, the north and south poles of a magnet cannot be separated. If a magnet is cut, each piece forms a smaller magnet with its own north and south poles. Magnetic poles always exist in pairs.

Q 5. how do magnet loose their magetism ?
Ans: Here are some very simple ways magnets lose their magnetism:
  1. Heating the magnet too much.
  2. Dropping or hitting the magnet repeatedly.
  3. Storing magnets carelessly.
Q 6. Suggest a method to separate a mixture of saw dust, iron filings and salt ?
Ans: To separate a mixture of sawdust, iron filings, and salt:
  1. Use a magnet: Move a magnet through the mixture to attract and separate the iron filings.
  2. Add water: Mix the remaining sawdust and salt with water. Salt dissolves, while sawdust floats.
  3. Skim or filter: Remove the floating sawdust using a strainer or spoon.
  4. Evaporate water: Heat the saltwater solution to evaporate the water, leaving salt behind.

Long Answers:

Q 1. Differentiate between magnetic and nonmagnetic substances. Give one example of each.

Ans.

Magnetic Materials: Those materials which are attracted by a magnet are magnetic materials. Iron, Nickel, and Cobalt are the magnetic substances as objects made up of these materials are attracted by a magnet.   

Non - Magnetic Materials: Those materials which are not attracted by a magnet are called non- magnetic materials. For example plastic, rubber, water, etc. are nonmagnetic materials.

Q 2. Write two main properties of a magnet.

Ans.

Properties of magnet:

v  Attractive Property – Magnet attracts ferromagnetic materials like iron, cobalt, and nickel.

v  Repulsive Property – Like magnetic poles repel each other and unlike magnetic poles attract each other.

v  Directive Property – A freely suspended magnet always points in a north-south direction.

Q 3. How can an iron rod be magnetized?

Ans. Magnetizing the Rod:  follow the below steps:

  • Take a strong magnet and rub it along the length of the iron rod.
  • Rub in the same direction, not back and forth, to help the domains align.

  • Continue rubbing for several minutes, and the rod will become magnetized.    


    • Q 4. Show that a magnet has two poles. What are the properties of the magnetic poles of a magnet?  

    Ans. A freely suspended magnet always comes to rest in the north – south direction. This shows that all magnets have two poles.

    Properties of magnetic poles:

    • Attractive Property – Magnet attracts ferromagnetic materials like iron, cobalt, and nickel.
    • Repulsive Properties – Like magnetic poles repel each other and unlike magnetic poles attract each other.
    • Directive Property – A freely suspended magnet always points in a north-south direction.

    Q 5. Mention three uses of magnets and electromagnets.

    Ans. Applications of magnets:

    1. Speakers and Microphones
    2. Magnetic Closures
    3. Compass
    4. Magnetic Separation

    Applications of Electromagnets: Electromagnets are very widely used in electric and electromechanical devices, including:

    1. Motors and generators.
    2. Transformers.
    3. Electric bells and buzzers

    HOTS:

    1. Why magnets should be kept away from electronic devices ?

    Ans: Magnets can interfere with electronic devices by disrupting magnetic fields, damaging data storage (e.g., hard drives), or affecting components like speakers and screens, leading to defect or data loss.

    2. Why is the compass needle enclosed in a cover ?

    Ans: The compass needle is enclosed in a cover to:

    1. Protect the needle
    2. Reduce environmental interference
    3. Minimize friction
    4. Prevent accidental misalignment 
    5. Enhance durability


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