Why is iron often used in electromagnets?

Iron is often used in electromagnets due to its high magnetic permeability and ability to enhance the magnetic field.

Iron is a ferromagnetic material, which means it is highly attracted to magnetic fields and can be magnetised itself. This property makes it an excellent choice for electromagnets. The high magnetic permeability of iron allows it to enhance the magnetic field produced by the electric current. This is because the magnetic field lines prefer to travel through the iron core rather than air, due to the lower magnetic reluctance (opposition to the magnetic field) of iron.

When an electric current is passed through a coil of wire wrapped around an iron core, the magnetic field produced by the current magnetises the iron. This magnetisation of the iron core then adds to the magnetic field produced by the coil, significantly increasing the overall magnetic field strength. This is why electromagnets often use iron cores - to increase the strength of the magnetic field they produce.

Furthermore, iron has a high magnetic saturation level. This means that it can be magnetised to a high degree before it reaches a point where further increases in the magnetising force do not result in an increase in magnetisation. This property allows electromagnets with iron cores to produce very strong magnetic fields.

However, it's important to note that iron also has a high magnetic hysteresis, meaning it tends to retain its magnetisation even after the magnetising force is removed. This can be a disadvantage in applications where a quick response to changes in the magnetising force is required. But for many applications, the advantages of using iron in electromagnets far outweigh this disadvantage.

In conclusion, the use of iron in electromagnets is primarily due to its high magnetic permeability, which allows it to enhance the magnetic field produced by the electric current. Its high magnetic saturation level also allows for the production of very strong magnetic fields.