FRICTIONAL FORCES

Magnetism is a force that can attract (pull closer) or repel (push away) objects that have a magnetic material like iron inside them (magnetic objects). Magnets can be affected by electricity, which makes them very useful in machines and computers. Magnets are used to make a tight seal on the doors to refrigerators and freezers, etc.

MEANING OF MAGNET

A magnet is a substance which can attract iron or steel material to itself.

Magnets are made of iron or steel.

 

TYPES OF MAGNETS

There are two types of magnets:

1. Permanent Magnets

Permanent magnets remain magnetized even without the influence of external magnetic field, such as a horseshoe magnet.

 

2. Temporary Magnets

Temporary magnets may lose their magnetism when removed from the external magnetic field, such as an iron pin.

 

See also

FRICTIONAL FORCES

FORCES

 

PROPERTIES OF MAGNETS

1. Magnets attract ferromagnetic materials, such as iron, nickel, and cobalt.

 

2. All magnets have two poles: North Pole and South Pole.

There are no magnets containing only one pole.

 

3. Like poles of two magnets repel each other; opposite poles of two magnets attract each other.

 

4. The magnetic force of a magnet is stronger at its poles than in the middle.

 

5. The stronger the magnets and the closer two magnets are to each other, the greater the magnetic force exerted on each other.

 

6. When a bar magnet is suspended by a thread freely in horizontal position, its north pole will move towards the North Pole of the earth and its south pole will move towards the South Pole of the earth. This is because the earth is a giant magnet, and its geographical north pole is its magnetic south pole, and vice versa.

 

USES OF MAGNETS

Magnets have their lot of applications in the daily life. The major 10 uses of the magnets are as follows:

 

1. They are also used to sort out the magnetic and non-magnetic substances from the scrap.

 

2. They are used in TV screens, computer screens, telephones and in tape recorders.

 

3. They are used by the candy or cold drink vendors to separate the metallic cap from the lots.
4. They are used in cranes.

 

5. They are also used in the speakers which can convert the electrical energy into sound energy.
6. They are used in the electrical bells.
7. They are used in the refrigerators to keep the door close.
8. The most important use of the magnet is the magnetic compass which is used to find the geographical directions.
9. They are used to construct the electrical motors and the generators which convert the electrical energy into mechanical energy and vice versa.
10. They are used in the Maglev trains. In the Maglev trains, the super conducting magnets are used on the tracks on which the train floats. These types of the trains are working on the repulsion force of the magnets.

 

MAKING A TEMPORARY MAGNETS

1. Rub the magnet against the paperclip.

 

2. Move it in the same direction, rather than back and forth.

 

3. Use the same quick motion you’d use to light a match.

 

4. Continue rubbing the paperclip with the magnet 50 times as quickly as you can.

 

See also

PULLEYS

LEVERS

 

Strategies & Activities

Step: Teacher revises the previous topic

Step 2: Teacher introduces the new topic.

Step3: Teacher endeavors to explain all the points to the pupils thoroughly.

Step 4: Teacher welcomes pupils’ questions.

Step 5: Teacher evaluates the pupils.

 

Assessment & Evaluation

1. State two of properties of a magnet;
2. Name three common appliances that use magnets;
3. Group materials into magnetic and non-magnetic materials;
4. Make temporary magnets.