Class Notes NCERT Solutions for CBSE Students
Question: Name and describe the instrument that uses a magnet to find direction.
Answer: The instrument that uses a magnet find directed direction is a magnetic compass. This magnet consists of magnetized needle pivoted at a point so that it can move freely. We have to rotate it till the north of the needle matches the north of the scale.
Question: List any three uses of magnet.
Answer: The three uses of magnet are:
Credit cards: In credit cards and ATM cards where information is stored in a magnetic strip.
Hard disks: In audio and video tapes and computer hard disks to store information.
Fridge magnets: In refrigerator door stickers, closing mechanism of refrigerator doors, bulletin boards and toys.
Question: Briefly explain how a magnet is demagnetized.
Answer: A magnet is demagnetized when:
- It is dropped from a height.
- If you hammer it.
- If you heat it.
- If you do not store it properly using keepers.
Question: Explain that repulsion is the sure test of magnetism.
Answer: When like poles of the magnets (N-N or S-S) are brought close to each other, they repel. This is called repulsion. Thus repulsion not attraction is the sure test of magnetism.
