Unit 4
Electromagnetism
Magnet
It is a piece of iron having the property of attracting objects made up iron, steel, cobalt, nickel.
The attracting property of a magnet is called magnetism [magnetic force of a magnet].
A magnet has two poles (north and south).
Magnetic poles are the parts of a magnet that exert the strongest force on other magnets
or magnetic material.
Magnetic poles can never be separated if we break a magnet into pieces. Magnetic poles
are always found in pairs.
So, when a bar magnet is divided into pieces:
New bar magnets are created
The magnetic force of each separated piece becomes weaker.
Magnet can be permanent magnet, temporary magnet or electromagnet.
i. Permanent magnet: is material where its magnetic property is generated by its internal
structure.
Once the permanent magnet is magnetized, it holds its magnetic property for a very long time.
ii. Electromagnet: is wound of wire [or coil] where its magnetism [magnetic force or field] is
generated when electric current is provided to it.
That is, magnetic force of an electromagnet is formed from electric current and is called
electromagnetism [electromagnetic force]. But when the current is off, the electromagnet loses
its electromagnetism.
To increase the strength of magnetic field of an electromagnet paced a magnetic material
like iron inside the coil.
All atoms are inherently magnetic because of the circulating electrons they contain.
When electrons of most substances revolve around the atom, they form equal and
opposite pairs of magnetic effects and cancelling out each other. But there is some
remainder. From this the magnetic effect for most substances is very small and they are
considered as non-magnetic materials.
The circulation of electrons of ferromagnetic materials such as iron, cobalt, nickel produces large
magnetic effect and they are called strong magnetic materials. From this, electromagnetism is a
fundamental force in nature consisting of the electricity and magnetism.
Electromagnetism
Magnet
It is a piece of iron having the property of attracting objects made up iron, steel, cobalt, nickel.
The attracting property of a magnet is called magnetism [magnetic force of a magnet].
A magnet has two poles (north and south).
Magnetic poles are the parts of a magnet that exert the strongest force on other magnets
or magnetic material.
Magnetic poles can never be separated if we break a magnet into pieces. Magnetic poles
are always found in pairs.
So, when a bar magnet is divided into pieces:
New bar magnets are created
The magnetic force of each separated piece becomes weaker.
Magnet can be permanent magnet, temporary magnet or electromagnet.
i. Permanent magnet: is material where its magnetic property is generated by its internal
structure.
Once the permanent magnet is magnetized, it holds its magnetic property for a very long time.
ii. Electromagnet: is wound of wire [or coil] where its magnetism [magnetic force or field] is
generated when electric current is provided to it.
That is, magnetic force of an electromagnet is formed from electric current and is called
electromagnetism [electromagnetic force]. But when the current is off, the electromagnet loses
its electromagnetism.
To increase the strength of magnetic field of an electromagnet paced a magnetic material
like iron inside the coil.
All atoms are inherently magnetic because of the circulating electrons they contain.
When electrons of most substances revolve around the atom, they form equal and
opposite pairs of magnetic effects and cancelling out each other. But there is some
remainder. From this the magnetic effect for most substances is very small and they are
considered as non-magnetic materials.
The circulation of electrons of ferromagnetic materials such as iron, cobalt, nickel produces large
magnetic effect and they are called strong magnetic materials. From this, electromagnetism is a
fundamental force in nature consisting of the electricity and magnetism.
