## Topic outline

• ### Fun with Magnets

##### Q20. How does a magnetic compass works?

Ans. The Earth behaves like a magnet and attracts the north end of compass magnet to align with its magnetic field. The north pole of the compass is attracted to the South Pole of Earth's built-in magnet and vice versa.

##### Q21. Can poles of magnet be isolated?

Ans. If a bar magnet is broken into two pieces, then each piece behaves as two separate magnets. Thus, it is observed that even the smallest piece of magnet has north and south poles. So, we cannot separate the two poles.

##### Q22. What is north seeking pole and south seeking pole of a magnet?

Ans. The end of the magnet that points towards North is called its North seeking end or the North Pole of the magnet. The other end that points towards the South is called South seeking end or the South Pole of the magnet.

##### Q23. Tom mixed some board pins with saw dust while doing his school project. How can he separate board pins from the saw dust without picking with his hands?

Ans. By using a magnet he can attract all the board pins from saw dust. This is possible since, the board pins are magnetic materials, whereas saw dust is a non-magnetic material.

##### Q24. Repulsion is the sure test of magnetism. Why?

Ans. Repulsion is the sure test of magnetism because repulsion can takes place only between two like poles of a magnet whereas attraction takes place between two unlike poles of a magnet and also between a magnet and a magnetic material.

##### Q25. What is a Magnetic compass? Where it is used?

Ans. A magnetic compass is usually a small box with a glass cover on it. A magnetized needle is pivoted inside the box, which can rotate freely. The compass also has a dial with directions marked on it. Its needle indicates the north-south direction when it comes to rest. It is used by sailors and navigators to know the directions.

##### Q26. Write some common uses of magnets.

Ans. Uses of magnets

1.   They are used in the refrigerators to keep the door close.

2.   They are used in magnetic compass.

3.   They are used in the electrical bells.

4.   They are used in speakers.

5.   They are used in TV screen and computer screen.

##### Q27. What are Magnetic Material and Non-Magnetic Material? Give examples.

Ans. The materials which get attracted towards a magnet are magnetic materials. Iron, nickel, cobalt and their alloy are magnetic materials.

The materials which are not attracted towards a magnet are non-magnetic materials. Plastic, rubber, leather, aluminium, copper, brass, stainless steel, wood etc. are non-magnetic materials.

##### Q28. Write the magnetic and non-magnetic substances from the list given below in respective column:Iron, Steel, Nickel, Plastic, Cobalt, Wood, Copper, a stainless steel spoon and leather

Ans.

 Magnetic Non-Magnetic Iron Plastic Steel Wood Nickel Copper Cobalt Stainless steel spoon Leather

##### Q29. Differentiate between Natural and Artificial Magnet.

Ans.

 Natural Magnet Artificial Magnet 1. A natural magnet is a magnet that occurs naturally in nature. 1. Magnets made by man are called artificial magnets. 2. Example: lodestone or magnetite 2. Example: cylindrical magnet, bar magnet, U-shaped magnet or horseshoe magnet. 3. Natural magnets are permanent magnets. 3. Artificial magnets can be temporary as well as permanent.