Exploring Magnets Class 6 Notes Science Chapter 4

Class 6 Science Chapter 4 Notes Exploring Magnets

→ Magnets: The substances having the property of attracting pieces of iron or some other magnetic substances are called magnets.

→ Types of Magnets: There are two types of magnets:

1. Natural magnets: Lodestones are called natural magnets and were discovered in ancient times. They can attract iron, cobalt and nickel.
2. Artificial magnets: The magnets formed by the pieces of iron are called artificial magnets. They may have different shapes.
   

→ Shapes of Magnets: There are various shapes of the magnets:

1. Bar magnets
2. U-shaped magnet
3. Ring magnet

→ Uses of Magnets:

1. It is used in refrigerator’s door, pencil boxes, toys and pin stand, etc.
2. It is used in picking up pieces of iron from wastes.

→ Types of materials on the basis of effect of a magnet:

→ There are two types of materials:

1. Magnetic materials: The materials which get attracted towards magnet are called magnetic materials. For example: iron, nickel and cobalt.
2. Non-magnetic materials: The materials which are not attracted towards a magnet are called non-magnetic materials. For example: wood, rubber or plastic.

→ Poles of Magnet: The ends of the magnet are called poles. There are two poles of a magnet:

1. North Pole: When a magnet is suspended freely, then one end of the magnet points towards north direction, that end of the magnet is called north pole. It is indicated by N.
2. South Pole: When a magnet is suspended freely, then the end which points towards south direction is called south pole of the magnet. It is indicated by S.

→ The poles of a magnet always exist in pairs. A single North pole or a single South pole cannot exist. A freely suspended magnet rests along the north-south direction.

→ Lodestone: The magnetic stone indicating directions used by sailors in old days to identify directions is called lodestone.

→ Interaction between two poles:

1. Like poles (North-North, South-South) repel each other.
2. Unlike poles (North-South) attract each other.

→ Strength of a Magnet:

1. The strength of a magnet is maximum at its poles.
2. The strength of magnet decreases as we go towards the mid-point of a magnet.
3. The strength of magnet is very less or zero at the mid-point of a magnet. It is called neutral point.

→ Magnetic compass: It is a small round box with a clear transparent cover. Inside, there is a needle-shaped magnet attached to a pin at the bottom.

→ This needle can spin easily around the pin. One end of the needle, which points towards the North, is painted red. Below the needle, there is a dial with directions marked on it.

→ The needle of a magnetic compass indicates the north-south direction.

→ When the North pole of a magnet is brought closer to the North pole of the compass needle, it moves away.

→ When the South pole of the magnet is brought closer to the North pole of the compass needle, it moves closer.

Introduction

Magnets are facinating objects that can attract materials like iron. They have been used for centuries, with sailors in ancient times relying on magnets compasses to navigate their ships.Magnets can be naturals, such as lodestones, or artificial, made from material like iron or other metals.

Todays, we find magnets in many everyday items, including pencil box, toys and even in school supplies. Magnets come in different shapes and sizes, serving various purposes in our daily lives, from keeping things closed to helping us find directions.

→ Attraction : The mutual pull of two bodies each other.

→ Conclude : Come to an end.

→ Bar magnet : A bar magnet is a long rectangular magnetised bar of iron or steel.

→ Construct : Build

→ Magnetic Compass : A magnetic compass is a simple device used by the pilots and navigators to find the direction in which their ship or aeroplane is going.

→  Experiment : Test or trial done carefully in order to study what happens and gain new knowledge.

→ Magnetic materials Those materials which are attracted by a magnet are called magnetic materials.

→ Explore Travel into or through in order to learn about it.

→ Non-magnetic materials : Those materials which are not attracted by a magnet are called non-magnetic materials.

→  Investigate : To explore.

→ North pole of a magnetic: The end of the magnet that points towards the north is called the north pole.

→ Observe : To see or notice.

→  Repulsion : Feeling of loathing or a traversion.

→ Predict : Forecast.

→  Ring magnet : A magnet having a ring shape is called “Ring Magnet”

→  Record : A permanent account especially in writing of facts, events, etc.

→ South pole of a magnet : When a magnet is suspended freely then the end which points towards south direction are called south pole of the magnet.

→  U-shaped magnet : A magnet having U-shape is called U-shaped magnet.

→ A magnet has two poles-the North pole and the South pole.

→  The poles of a magnet always exist in pairs. A single North pole or a single South pole cannot exist.

→ Magnetic materials are the materials that are attracted towards a magnet.

→ Non-magnetic materials are the materials that are not attracted towards a magnet.

→ A freely suspended magnet rests along the north-south direction.

→ The needle of a magnetic compass indicates the north-south direction.

→ When two magnets are brought close to each other, like poles (North-North, South-South) repel each other while unlike poles (North-South) attract each other.

→ A magnetic compass is a freely suspended magnetic needle, placed in an aluminium box, at the base of which are marked geographical directions. It is used by the sailors and navigators for finding directions of a given place.

→ The process by which a magnet loses its magnetism is called demagnetisation.

→ The soft iron pieces which are used to avoid de-magnetisation of magnets during storage are called magnetic keepers.

→  Magnetic and Non-magnetic Materials : The materials which are attracted towards a magnet are called magnetic materials. The metal iron is a magnetic material. Nickel and cobalt are other metals that are also magnetic. Steel or other alloys of iron are magnetic substances. A mixture of ferric oxide and barium oxide is strongly magnetic in nature. It is commonly called ferrite. It is used for making very powerful magnets for radios and transistors.

→ The materials which are not attracted towards magnet are called non-magnetic materials. Stones, chinaware, glass, wood, paper, brass, aluminium, mica, ebonite, gold, silver, etc are non-magnetic substances.

→  A Magnetic Compass : Magnetic compass was developed in older days for finding directions. A magnetic compass is usually a small circular box with a transparent cover on it. The magnet in the shape of a needle, is mounted on a pin standing on the bottom of the box. This needle is balanced on the pin in such a manner that it can move around the point easily, that is, it can rotate freely.

The end of the needle which rest in the North direction is usually painted red. Below the needle, there is a dial with directions marked on it. The compass is kept at the place where we wish to know the directions. After sometime, the needle comes to rest in the north-south direction. The compass box is then gentlty rotated until the north and south marked on the dial are aligned with the needle. Now all directions at that place are as indicated on the dial.

→  Modern Magnetic Compass : It consists of a magnetised fishshaped iron piece, kept in a vessel of oil. It was called matsyayantra (or machchh-yantra)

Fun With Magnets

(i) We can make a garland. (Fig. 11)
(ii) We can take the steel balls out of the maze by moving a magnet below the cardboard tray. (Fig. 12)

(iii) We can pick out a șteel paper clip fallen in water using a magnet, without making our fingers or the magnet wet. (Fig. 13)
(iv) Two cars will speed towards each other or run away from each other when brought closer. (Fig. 14)

Important Information

In some magnets, the North and South poles are marked as N and S . In some other magnets, the North pole is indicated by a white dot. Sometimes, the North pole of a magnet is painted red and South pole is painted blue.

How to Keep the Magnetic Safe ?

1. To avoid self-demagnetisation, magnets are kept in such a way that their opposite poles are joined. This is done by placing soft iron pieces (called keepers) across both the ends. A wooden piece may be kept in between the two bar magnets.
2. A magnet should not be taken near heat as it loses its magnetism.
3. A magnet should not be hammered or dropped on a hard surface.

Class 6 Science Notes