PHYSICS NOTES - CH - 6 - MAGNETISM - UNIT 1 - NATURAL AND ARTIFICIAL MAGNETS (ADHVEY's NOTES)

Formal Notes: Magnetism

Unit 1 - Natural and Artificial Magnets.

Answer the following questions:

Q1 (a) What is a magnet?

Ans: Magnet: A magnet is a substance which has a property of attracting other magnetic substances such as iron, steel, nickel and cobalt, and when freely suspended always points in north south direction.

Q1 (b) What is a natural magnet? Name the chemical formula of it.

Ans: Natural Magnet: A material which occurs naturally and has magnetic properties is called natural magnet. Magnetite (Fe3O4) is a naturally occuring magnet.

Q2 (a) What are artificial magnets?

Ans: Artificial Magnet: A substance to which properties of a natural magnet is imparted by artificial means is called an artificial magnet.

Q2 (b) Draw neat diagrams of four different shapes of artificial magnets.

Ans.

Q3. Why are artificial magnets preferred over natural magnets?

Ans: Reasons for using artificial magnets:-

(i) They can be made very powerful which is not possible in the case of natural magnets

(ii) They are made in any desired shape or size. It is not possible in case of natural magnets which breaks when shaped with cutting tools.

Q4. Name four devices which use artificial magnets.

Ans: Use of Artificial Magnets in devices:

(i) Telephones (ii) Television (iii) Loudspeakers (iv) Radio

Q5. What is ferrite? What are its uses?

Ans: Ferrite: A mixture of ferric oxide and barium oxide is strongly magnetic. It is commonly called ‘ferrite’.

It is used for making very powerful magnets for radios and transistors.

Q6. Define and give four examples.

(a) Magnetic substances 

(b) Non-Magnetic Substances

Ans: (a) Magnetic Substances: 

The substances which are strongly attracted by magnet or can be converted into magnet artificially are called magnetic substances. For eg: Iron, cobalt, nickel, steel or their alloys.

(b) Non-Magnetic Substances: 

The substances which are neither attracted by magnet nor can be converted into artificial magnets are called non-magnetic substances. For eg: Stones, glass, wood etc.

Q7. Why is a 10 rupees coin attracted by a magnet? Name the metal present in the coin.

Ans: 10 rupees are made with nickel. Since nickel is a ferromagnetic substance, it is attracted by a magnet.