Category :
6th Class
Fun With Magnets
Synopsis
- Substances that can attract iron are called magnets.
- Substances can be divided into magnetic and non-magnetic substances.
- Substances that are attracted by a magnet are called magnetic substances. Usually things made up of iron, nickel or cobalt are magnetic.
- Substances that are not attracted by a magnet are called nan-magnetic substances. Paper, plastic and wood are a few examples of non-magnetic substances.
- Magnets are divided into two groups - natural and artificial magnets. Magnetite (lodestone) is a naturally occurring magnet.
- Artificial magnets can be of many shapes and are commonly used in different articles like electric bells, radio, etc.
- The magnetic force or the force of attraction in a magnet is concentrated at the two ends of a magnet. These ends are called poles. They are called the north pole and the south pole.
(i) There are always two poles in a magnet placed at opposite ends. This holds true even if we break or cut the magnet into smaller pieces. Each piece
will have two poles.
(ii) When two different magnets are brought closer, like poles repel and unlike poles attract each other.
(iii) A magnet, when suspended freely, always comes to rest in a line along the north-south line of that place.
- The bar AB (of iron or steel) to be magnetized is stroked with a bar magnet from one end to the other using the same pole as shown in the figure. This process is repeated for about 50 times.
- The end A from where the process starts develops the same polarity as the pole of the magnet stroking and the other end develops the opposite polarity.
- Magnets lose their properties when they are heated, hammered or dropped and if they are not stored properly.
- Magnetism is widely used to make articles like cassettes, computers, T.V., ATM cards, etc.
