A magnet is a piece of metal that can attract some other metals.
1. Magnetism is a form of energy that enables a magnet to push or pull other objects without touching them.
- The space or area around a magnet where it extends its force of magnetism is called a Magnetic field.
- In the magnetic field, effects of attraction and repulsion can be detected.
- The lines around a magnet along which the magnetic force moves are called lines of force or lines of flux.
- The lines of force of a magnet run from the North Pole to South Pole.
The ends of a magnet are called poles. A magnet has North Pole and South Pole.
- These are materials that can be attracted by a magnet.
- Such materials may contain IRON, NICKEL AND COBALT.
- We can therefore say Iron, nickel and cobalt are the magnetic metals.
- All materials that contain any of the above three metals can be attracted therefore they are magnetic.
- These are substances that can not be attracted by a magnet.
- Such materials include, wood, plastic, cloth, papers copper aluminium, silver etc.
Metals that are non magnetic materials.
TYPES OF MAGNETS:
There are two types of magnets.
- Temporary Magnets
- Permanent Magnets
- Permanent magnets can be natural or artificial magnets.
- These are magnets that do not lose magnetism even after the source has been removed.
- A natural magnet was first discovered in a place called Magnesia. Magnets derive their name from that place.
- The natural rock, which could attract other metals, was named Lodestone or magnetite
- Therefore an example of a natural magnet is Lode stone or Magnetite.
- The earth is also a natural magnet. This is because when a bar magnet is freely suspended it is attracted by the earth and it rests pointing in the North South direction.
- magnets are of different shapes.
Shapes of Artificial and permanent Magnets:
These are magnets that posses that force of magnetism once the source is still present.
They lose their magnetism once the source is removed. they are therefore magnets that last as long as their source of magnetism is still present.
Electro Magnets and Induced magnets are the examples of temporary magnets.
Some induced magnets can turn permanent depending on the strength of the source of magnetism and the length of time they stay attracted to the magnetism source.
PROPERTIES OF MAGNETS:
- A freely suspended bar magnet will rest pointing in the North-South direction.
- This property is used to make compasses that show direction.
- Sailors, Navigators, Tourists and pilots use this property to help them find direction.
2. Magnets are strongest at the poles.
Most fillings collect around poles. This indicates that magnets are strongest at the poles.
3. Like poles of a magnet repel each other while unlike poles attract each
1. Magnets are made by Magnetisation. Magnetic materials are turned into magnets.
2. Magnets can only be made from magnetic materials.
3. Alloys when magnetised become strong magnets that do not easily lose magnetism.
4. Steel is one example of an alloy that can be magnetised.
How magnetic materials become magnets
- Magnetic materials have particles known as domains.
- Before magnetic materials become magnets the domains are disorganised in arrangement.
Making permanent magnets
Permanent magnets can be made using either induction method or stroking method.
1. This is when a new magnet is produced by rubbing a magnet over a magnetic material.
2. There are two ways of stroking;
- Single touch Method
- double stroke Method or Divided touch.
Single Touch Method:
- This is when one magnet is used to stroke on a magnetic rod to produce a new magnet.
- It is done several times in the same direction with one pole of a magnet. When the end is reached the magnet is lifted high above and the stroking begins again.
- The end of the magnetic rod the magnet strokes last becomes the opposite pole of the stroking pole.
Double Touch Method or Divided Touch Method:
1. This is a method of stroking a magnetic material using two magnets.
2. Different poles of the magnet are used on either sides of the magnetic material.
3. The stroking starts from the middle moving to opposite poles.
4. Each pole used for stroking produce the opposite pole.
Making temporary magnets:
There are two methods of making temporary magnets. These are:
- Induction method
- Electrical method (electro-Magnetisation)
- This is a method of making magnets by making a piece of magnetic material to be in contact with a permanent magnet.
- When other materials are brought near the magnetic material they become attracted.
- The magnetic material now becomes an induced magnet.
- The induced magnet can lose its magnetism when removed from the permanent magnet.
- During the induction method the part of the magnetic material attached to the Magnet gets the opposite pole. The part at the end gets a similar pole to that at the pole of attachment.