Magnetism – CBSE NCERT Class VI Science lesson
Imagine if you wake up one day and find that you have the ability to attract things towards yourself! Then that would be real fun. Isn’t it? Well, there is a material in this world which attracts iron objects towards itself.It’s called a Magnet. Magnets can pull or push things made of nickle, cobalt, iron and steel.So these materials are referred to as Magnetic Substances. And those materials like plastic, paper, cloth etc. which are not affected by a magnet are called non-magnetic substances. Natural magnets are magnets made from loadstone. Artificial magnets are those magnetic materials which can be converted into magnets. Magnets can be temporary.. that is attract magnetic materials only for some time or permanent. That is they can always remain a magnet. Magnets can be of many shapes too. Here are some of them: A bar magnet, a horse-shoe magnet, a disc shaped magnet or a cylindrical magnet. Children do you know that you can convert any piece of iron into a magnet. Try this. Take an iron nail, rub a magnet on the nail for about 20 to 30 times in the same direction with the same end of the magnet. And Bingo! you will get another temporary magnet. Now rush. Pick up some Al-pins with them. This ability of magnets to attract or repel magnetic particles is called Magnetism and the area around a magnet in which the effect of the magnet can be experienced is called magnetic field. Magnets, can either pull or push objects that enter their magnetic field. Let me now tell you about the properties of a magnet. Magnets exert their influence through various materials. The effect of magnet works through air, water and even through solid things. Children, try putting some pins into a glass and bring a magnet near the glass. See what happens. Now add some water into the glass and repeat the action. What do you see? Magnets exert more magnetic force at the ends as compared to the middle. Try rolling a bar magnet on a plate containing iron filings. You will find that more filings stick on the ends. The ends of the magnets show more magnetic force and are called the poles of the magnet. A magnet always comes to rest in north south direction. Suspend a bar magnet with the help of a thread tied at its center. When it comes to rest you will find that its resting in the north-south direction. The pole pointing towards the north is called the North Pole and the pole which points towards the south is called the South Pole. Based on this property of a magnet a simple device called a Compass is designed.
A magnetic needle is allowed to rotate freely inside a small circular box made of brass or aluminum. Since the needle is a magnet, it comes to rest only in the north south direction. The end pointing north is usually painted red. Like poles repel, unlike poles attract each other. If two bar magnets are kept end to end then you will find that either the two magnets will stick to each other with a lot of force or it will be difficult to bring them together. This is because the north pole of one magnet attracts the south pole of the other magnet in the first case. And in the next case the north pole of one magnet strongly repels the north pole of the other magnet.
Magnetic poles always exist in pairs. If a magnet is broken, then each piece will behave as a complete magnet. So children, isn’t a magnet very fascinating? Enjoy magnetizing and have fun. Thank you.