We all have played with the magnets. But, have you ever wondered about its origin? The story of the discovery of the magnetic substances is interesting but more interesting is the scientific study of the cause of this force. Each magnet produces a force which is unique. Let us study the magnet and its properties.
The Story of Magnet
There is an island called Magnesia in Greece. Years ago, shepherds here complained that their wooden shoes with nails stayed stuck to the grounds. They were unable to walk further. This was the story behind the discovery of magnetism. So, how did this relate to the presence of magnetic fields? Actually, this island had lots of magnetic ore deposits!
Sounds really interesting! Doesn’t it? Let us now look at this topic in greater detail and discuss magnets and their properties. The property of an object by virtue of which it can attract a piece of iron or steel is called magnetism. The object itself is called a magnet. Now, we will look at the types of magnets.
Browse more Topics under Magnetism And Matter
- Magnetic Properties of Materials
- Magnetisation and Magnetic Intensity
- Permanent Magnets and Electromagnets
- The Bar Magnet
- The Earth’s Magnetism
A natural magnet is an ore of iron that attracts small pieces of iron, cobalt, and nickel towards it. It is usually an oxide of iron named Fe3O4. Magnetite or lodestone is a natural magnet.
A magnet that is prepared artificially form the artificial magnets. Examples include an electromagnet, a magnetic needle, horseshoe and bar magnets etc. According to the molecular theory, every molecule of a magnetic substance, irrespective of whether or not it is magnetized.
The poles are the two points near but within the ends of the magnetic materials, at which the entire magnetism can be assumed to be concentrated. The poles always occur in pairs and they are of equal strength. Like poles repel each other and unlike poles attract each other. This is all the basic information about magnets. Now, we will look deeper into the properties of magnets.
Video on Magnetic Effects of Current and Magnetism
Properties of Magnets
- Magnets attract magnetic substances like steel, cobalt, iron etc. This is also known as its attractive property.
- When a bar magnet is freely suspended, it points in the north-south direction. The tip which points to the geographic north is called the north pole and the tip which points to the geographic south is called the south pole. This is also known as its directive property.
- There is a repulsive force when north poles (or south poles) of two magnets are brought close together. Conversely, there is an attractive force between the north pole of one and the south pole of the other. This states that unlike poles attract each other and like poles repel each other.
- We cannot isolate the north or south pole of the magnets. If magnets are broken into two halves, we get two similar bar magnets with somewhat weaker properties. Unlike electric charges, isolated magnetic north and south poles known as magnetic monopoles do not exist.
Solved Examples For You
Q: If a bar magnet is cut lengthwise into 3 parts, the total number of poles will be:
A) 2 B) 3 C) 4 D) 6
Sol: D) Magnetic monopoles can’t exist. Therefore, no matter how low you go to (atomic or subatomic level), you will always find a magnetic dipole. Magnets have to have at least one North and one South Pole. So when the bar magnet is cut into 3 parts, every part will have its own poles and thus the total number of poles will be 6.