Imp Questions For All Chapters – General Science Class 7
Properties of a Magnetic Field
Short Questions
1. What is a magnet?
→ An object that attracts iron, nickel, and cobalt.
2. Name the two poles of a magnet.
→ North Pole (N) and South Pole (S).
3. What happens when like poles are brought together?
→ They repel each other.
4. What happens when opposite poles are brought together?
→ They attract each other.
5. What is a magnetic field?
→ The area around a magnet where its force is felt.
6. What is a compass used for?
→ Finding directions.
7. What is the real test of a magnet?
→ Repulsion, as only like poles repel.
8. Can a magnet attract through paper or water?
→ Yes, the magnetic field passes through them.
9. Which metals are attracted by a magnet?
→ Iron, nickel, and cobalt.
10. How are artificial magnets made?
→ By the Single-touch and Double-touch methods.
11. What is an electromagnet?
→ A temporary magnet made using electric current.
12. How does a magnetic needle work?
→ It always points north-south due to Earth’s magnetic field.
13. Give an example of an object using electromagnets.
→ Electric bell, MRI machine, crane.
14. Why do iron filings align around a magnet?
→ They follow the magnetic field lines.
15. Why do magnets lose strength over time?
→ Due to heat, impact, or strong external fields.
Long Questions
1. What is a magnetic field and how can we observe it?
→ A magnetic field is the invisible force around a magnet. We can observe it by sprinkling iron filings around a magnet, as they align along the field lines.
2. What are the properties of a magnet?
→ A magnet has two poles (North and South), like poles repel each other, opposite poles attract, and it has an invisible magnetic field around it.
3. How is an artificial magnet made?
→ An artificial magnet is made by rubbing a bar magnet repeatedly over an iron object in one direction (Single-touch or Double-touch method).
4. Why do we use soft iron for making electromagnets?
→ Soft iron is used because it quickly gains magnetism when current flows and loses magnetism when current stops, making it useful for electromagnets.
5. How does a compass work?
→ A compass contains a small magnetic needle that aligns itself with the Earth’s magnetic field, always pointing north-south.
6. Why do like poles repel and unlike poles attract?
→ Like poles have similar magnetic fields that push away each other, while unlike poles have opposite fields that pull each other together.
7. What is the importance of magnets in daily life?
→ Magnets are used in compasses, electric motors, speakers, MRI machines, and electronic devices to perform various tasks.
8. What happens if a bar magnet is cut in half?
→ Each half will form a new magnet with its own north and south poles, because magnetism is present throughout the material.
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