Interaction Between Magnets – Activity , Explanation

Interaction Between Magnets 

 Key Concepts

• Compass
• Interaction between magnets
• Earth – A giant magnet

Introduction

When a bar magnet is freely suspended, it always rests in the Earth’s geographic north-south direction. Even if it is disturbed several times, it always comes to rest at the same direction. In this section we shall discover the mystery behind this occurrence.  

Explanation

A compass: 

The property of the magnets by virtue of which it aligns itself always in the Earth’s geographical north-south direction was used for showing directions in olden days. Later on, people developed a device called compass and used it to show directions. A compass has a magnetized needle pivoted inside a small box with glass cover. It has a dial where the directions such as east, west, north and south are marked. The needle in the compass is a small magnet which is free to rotate about the pivoted point. It always aligns itself in a North-South direction. 

Steps to use a compass: 

• The compass is placed at a place where the direction is required. 
• Now, the compass needle aligns itself along the geographic north-south direction. 

• The north pole of the needle is generally painted in a different color. 
• The compass is then rotated to bring the north-south line of the dial coincide with the north and south side of the needle. 

Hence, all the directions are shown in the compass. 

Interaction between magnets: 

The interaction between magnets can be studied by conducting the following activity. 

Activity: 

For this activity we will need, 

1. Two bar magnets 

2. A thread 

3. A holder 

Steps: 

• Hang a magnet using a thread as shown in the picture. 
• Now bring the south pole of the second magnet close to the first one. 

• It will be observed that, the north pole of the first magnet moves towards the south pole of the second magnet. 
• Now flip the poles of the second magnet quickly so that the north pole of the first magnet is now close to the north pole of the first magnet. 
• It will be observed that, the north pole of the first magnet moves away from the north pole of the second magnet. 
• And, the south pole of the first magnet moves towards the north pole of the second magnet. 

Conclusion: 

These observations suggest that the north pole of a magnet is attracted towards the south pole of another magnet and vice versa. Also, the north pole of a magnet repels the north pole of another magnet. It follows that the south pole of a magnet repels the south pole of another magnet. The unlike poles of the two magnets attract each other. Whereas their like poles repel each other. 

Earth- A Giant Magnet: 

The conclusion drawn in the above activity can in other words be expressed as, the presence of a south pole moves a north pole towards it and a south pole away from it, and the presence of a north pole moves a south pole towards it and a north pole away from it.  

When the south pole of the bar magnet is brought close to the compass, the north pole of the compass needle rotates and moves towards it, and the south pole of the compass needle moves away from it. 

When the north pole of the bar magnet is brought close to the compass, the south pole of the compass needle rotates and moves towards it and, the north pole of the compass needle moves away from it. 

These observations indicate that Earth itself is a giant magnet. In fact, earth behaves as if it has a huge bar magnet inside it. 

The Earth has two sets of poles; geographic north and south poles, and magnetic north and south poles. The Earth’s magnetic north pole is located close to its geographic south pole. The Earth’s magnetic south pole is located close to its geographic north pole. Hence, the north pole of the compass needle actually gets attracted towards the Earth’s magnetic south pole and points towards it. And, the south pole of the compass needle actually gets attracted towards the Earth’s magnetic north pole and points towards it. The compass needle roughly points towards the geographic north-south direction of the Earth. 

Summary

1. A compass has a magnetized needle pivoted inside a small box with glass cover. It has a
   dial where the directions such as east, west, north and south are marked. It is used for
   locating directions.
2. The unlike poles of two magnets attract each other. Whereas their like poles repel each
   other.
3. The compass needle moves and changes its initial alignment only in the presence of
   another magnet.
4. The Earth is a giant magnet.
5. The Earth has two sets of poles; geographic north and south poles and magnetic north
   and south poles, located close to each other.
6. The compass needle exactly points towards the magnetic north-south direction of the
   Earth.
7. The compass needle roughly points towards the geographic north-south direction of
   the Earth