What is Electromagnet?
Electromagnets are made out of a coil of wire (wire curled in series). This is more effective in producing a magnetic field than just a wire running straight. This effect can be strengthened by winding a wire tightly around a powerful core, made of magnetic material, such as iron. The picture above shows a coil wound around an iron nail. On its own, the iron nail is not magnetic.
Properties of Magnet
A few properties of the magnet are as follows:
- Attractive Property – Ferromagnetic materials like iron, nickel and cobalt are attracted by magnets
- Repulsive Property – Like poles repel each other while unlike poles attract each other
- Directive Property – A freely suspended magnet always points in the north-south direction
Working Principle of Electromagnets
So how do electromagnets work? Let’s consider the iron nail itself. Why does it not produce a magnetic field when not influenced by an electric field?
An iron nail made into a magnet by passing electric current through a coil surrounding it.
Normally, the atoms in the nail are oriented in random directions and individual magnetic fields cancel each other out. Under the influence of electric current, these atoms are reoriented to start pointing in the same direction. All these individual magnetic fields together create a strong magnetic field. As the current flow increases, this degree of reorientation also increases, resulting in a stronger magnetic field. Once all the particles are reoriented perfectly in the same direction, increasing current flow will not affect the magnetic field produced. At this point, the magnet is said to be saturated.
Lines of Force around an Electromagnet
When the current passes through the wire it behaves like an electromagnet due to this current magnetic field will produce around the conductor. This field has its own north and south poles. It starts from the north pole and end at the south field. The strength of the field is higher at the center of the loop of the wire. And the strength decreases as moves away from the center.
If we wound more loops of the windings around the iron piece than the strength of the field can be increased. From this, we can conclude that the flux of any conductor is directly proportioned the amount of current passing through it and its number of the turns.
MMF = I x N
In this equation, MMF is Magneto-motive force, N is the number of turns and I is the current in amperes.
Magnetic Strength of the Electromagnet
- In the Electromagnet, there are 2 conductors used first one is wire loop and other is conductor whose around the loop is wound.
- When the current passes through these conductors magnetic field produced in both the conductors and these fields interact with each other and force act on these 2 conductors.
- If the current passing through both the conductors has a similar direction then the conductors will have attraction among them you can see it in the above diagram.
- When the direction of the current is opposite then the field of 2 conductors become strong and both of them repel each other.
Advantages of Electromagnets
Some electromagnet uses are given in the points mentioned below:
- Particle Accelerators
- Amplifiers
- Magnetic Separation
- Electric Motors and Generators
- MRI machines
- Control Switches in Relays
- Transportation
- Spacecraft Propulsion Systems
- Induction Heating
- Hard Drives
Disadvantages of Electromagnetism
A few disadvantages of electromagnetism are as follows:
- They heat up very fast
- It consumes a lot of energy
- They can store huge amounts of energy in their magnetic field. If the electric current is interrupted, the energy will discharge
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