Permanent magnets and electromagnets are two main types of magnets. A permanent magnet is called a permanent magnet because of ability to generate and retain its own persistent magnetic field. An electromagnet on the other hand is made from a coil of wire wrapped around a ferrous core and requires an electric current to generate a magnetic field. The magnetism of an electromagnet can be controlled and turned off and on using a switch, as its magnetism depends on a constant flow of electricity.
What Is Permanent Magnet/Bar Magnet?
A permanent magnet is a type of magnet made from a material that is magnetized and creates its own persistent magnetic field. The strength of a permanent depends upon the material used in its creation. Materials that are used in creation of this type of magnet are commonly referred to as ferromagnetic and they include iron, nickel and cobalt.
The main advantage of a permanent magnet over an electromagnet is that, a permanent magnet does not require a continuous supply of electric current to maintain its magnetic field.
To make a permanent magnet, ferromagnetic material is heated at incredibly high temperatures while exposed to a strong external magnetic field. This causes the individual magnetic domains within the material to line up with the direction of the external magnetic field to the point when all the domains are aligned and the material reaches its magnetic saturation point. The material is then cooled and the aligned domains are locked in position. This alignment of domains makes the magnet anisotropic. After the external magnetic field is removed, hard magnetic materials will keep most of the domains aligned, creating a strong permanent magnet.
Types of Permanent Magnets
The various types of permanent magnets are as follow:
- Ceramic magnet
- Alnico magnets
- Flexible magnets
- Neodymium iron Boron Magnets (NdFeB)
- Samarium Cobalt (SmCo) Magnet
What You Need To Know About Permanent Magnet (Bar Magnet)
- They are permanently magnetized.
- A permanent magnet produces a comparatively weak force of attraction.
- The polarity of a permanent magnet is fixed and cannot be reversed.
- It cannot be easily be demagnetized.
- It produces a permanent magnetic field.
- They are usually made from hard iron/steel.
- The strength of permanent magnets depends upon the nature of the material used in its creation.
- A bar magnet is a good example of a permanent magnet.
What Is An Electromagnet?
An electromagnet is a type of magnet whose magnetic field is created by the flow of electric current. An electromagnet is made from a coil of wire which acts as a magnet when an electric current passes through it. Usually, an electromagnet is wrapped around a core of ferromagnetic or ferromagnetic material like steel or iron which enhances the magnetic field produced by the coil. The magnetic core concentrates the magnetic flux and makes a more powerful magnet.
An electromagnet loses its magnetic strength every time an electric current is removed and becomes magnetic once again when the electric current is introduced. Also, the poles of an electromagnet can even be reversed by reversing the flow of electricity.
The main advantage of an electromagnet over permanent magnet is that, its magnetic field can be rapidly manipulated over a wide range by controlling the amount of electric current supplied to the electromagnet.
Electromagnets are used in much electric device application including:
- Electric bells
- MRI machines
- Industrial lifting magnets
- Magnetic locks
- Magnetic recording and data storage equipment
- Magnetic separation of materials
- Motors and generators
What You Need To Know About An Electromagnet
- They are temporarily magnetized.
- An electromagnet can produce very strong magnetic force.
- The polarity of an electromagnet can be reversed by changing the direction of current in its coil.
- It can easily be demagnetized by switching off the current.
- It produces a magnetic field as long as the current flows through its coil.
- They are usually made from hard iron/steel.
- The poles of electromagnet can be changed by flow of current.
- The strength of electromagnets depends upon the quantity of flow of current.
- A solenoid is a good example of an electromagnet.
Difference Between Permanent Magnet And Electromagnet In Tabular Form
|BASIS OF COMPARISON||PERMANENT MAGNET||ELECTROMAGNET|
|Description||They are permanently magnetized.||They are temporarily magnetized.|
|Force Of Attraction||A permanent magnet produces a comparatively weak force of attraction.||An electromagnet can produce very strong magnetic force.|
|Polarity||The polarity of a permanent magnet is fixed and cannot be reversed.||The polarity of an electromagnet can be reversed by changing the direction of current in its coil.|
|Demagnetization||It cannot be easily be demagnetized.||It can easily be demagnetized by switching off the current.|
|Magnetic Field||It produces a permanent magnetic field.||It produces a magnetic field as long as the current flows through its coil.|
|Creation||They are usually made from hard iron/steel.||They are usually made from hard iron/steel.|
|Strength||The strength of permanent magnets depends upon the nature of the material used in its creation.||The poles and strength of an electromagnet can be changed by flow of current.|
|Examples||A bar magnet is a good example of a permanent magnet.||A solenoid is a good example of an electromagnet.|
Similarities Between Permanent magnets and Electromagnets
- Both magnets have the capability to exhibit the properties of magnetism
- Both magnets have north and south-pole whose behavior depends on the geographic north-pole and south-pole of the earth.
- Both magnets possess imaginary magnetic field lines.