Les 3 prime 5

By master Mohamed talaat

Lesson 3: magnetism What is the magnetism?

It is attractive force of natural magnet What is the natural magnet?

It is black rocks have attractive force to any material made of iron What is magnesia? it is area in Greeks which found in it natural magnet.

Types of magnet: 1- Natural magnet (magnetite): it is one of the iron ores, and has color is black.

2- Artificial magnet: Have different shapes and sizes may be rectangular magnet, horse-shoe, needle, bar, and ring magnet.

Types of material: A) Magnetic materials: they are materials which are attracted to the magnet, as iron, nickel, steel, cobalt b) Non-magnetic materials: they are materials which are not attracted to the magnet, as chalk, glass, aluminum, copper, wood, Leather, plastic.

G R) iron attracts to the magnet but copper doesn`t attract?

Properties of the magnet: 1- Has two poles 2- Suspended magnet is free move 3- Similar magnetic poles repel each other, but different magnetic poles attract to each other.

4- Has magnetic field.

Now we will study each one.

First: magnet has two poles.

Activity1: approach a bar magnet to the metallic paper clips what you see.

Observation: the greatest number of the metallic clips are attracted at the two poles( ends) of the magnet, and disappear in the middle of the magnet.

Inference: two poles of magnet( magnetic poles): it is the areas of magnet at which the most of attraction force is concentrated.

G R): paper clips are attracted at poles of the magnet?

Second: suspended magnet move free Activity2: suspend a bar magnet from its centre and leave it until stabilizes horizontally.

Observation: one of pole points to north, and the other pole points to south.

Note: North Pole (N): the pole of magnet which points to north direction.

South Pole(S): the pole of magnet which points to south direction.

Third:similar magnetic poles repel each other , but opposite magnetic poles attract each other Complete 1-when you approach the north pole of the magnet to the north pole of another magnet they will……………….

2-when south pole of the magnet approach to North Pole of another magnet the will……………………

G R)1- the north pole of a magnet attracts to the south pole of another magnet, but repels to north pole?

Because the opposite magnetic poles attract to each other, while the similar magnetic poles repel to each other.

Forth : the magnet has magnetic field What is the magnetic field?

It is the area around the magnet in which the effect of magnetic force appears.

What is the magnetic force?

Magnetic force: it is the ability of the magnet to attract the magnetic materials existed in its field.

The uses of the magnet 1- Making the magnetic compass

What is the idea of compass?

It is the magnetized needle.

Structure of compass: the compass consists of magnetized needle( light and small magnet) can spin freely around a fixed axis where the north pole refers to north direction of earth,and south pole refers to the south direction of earth The importance of magnetic compass: it used to determine the four geographical directions.

G R) the compass is used to determine the main four directions?