Physics

Difference Between Hard and Soft Iron

Main difference

The main difference between hard iron and soft iron is that hard irons are ferromagnetic substances that cannot be easily demagnetized once they are magnetized by a forced change in magnetic field. While small soft irons are ferromagnetic substances that can be easily magnetized and re-magnetized with a change in magnetic field.

Hard Iron vs. Soft Iron

Hard iron is the type of metal that, if magnetized once, cannot be easily demagnetized. It means that if a hard iron is magnetized once, it will not be easy to demagnetize it. However, soft irons can be re-magnetized with the use of a small change in electrical force which differentiates them from hard iron due to this specific characteristic. Therefore, hard irons are known as hard magnetic material, while soft irons are called soft magnetic material. Hard irons have their applications as permanent magnets and are used commercially where this specific property of these materials is required, while soft irons are used as electromagnets. They have their uses as parts of electric motors and generators.

Hard irons have low susceptibility, since once magnetized, or their atoms are aligned, it doesn’t flip or change as easily. On the other hand, soft irons have a high susceptibility and their alignment of atoms changes easily with the change in the electric field around them. Hard irons have high retentivity as they have a higher retention for any changes made and it is almost impossible to reverse the alignment. On the other hand, soft irons have a lower retention rate as their arrangement of atoms is only temporary, and due to this property, they can be easily re-magnetized and are used as soft magnets or electromagnets.

Comparison chart

hard iron soft iron
The type of iron that if magnetized once cannot be easily demagnetized The type of iron that can be re-magnetized with the use of changes in electrical force.
Magnetic Property
These are hard magnetic materials These are soft magnetic materials
Re-magnetization
Once magnetized, it cannot be easily re-magnetized. Once magnetized it can be easily re-magnetized.
Susceptibility
Hard irons are less susceptible Soft irons are more susceptible
remanence
Hard irons have more retention of the magnetizing effect. Soft plates have less retention of the magnetizing effect.
Alignment of Atoms
The alignment of atoms is almost permanent The alignment of atoms is temporary

What is hard iron?

Ferromagnetic substances possess magnetization in the absence of an external magnetic field. Hard iron is the type of ferromagnetic material that if magnetized once cannot be easily demagnetized, making it a hard iron as the name suggests. This property differs from soft iron and has its uses for this distinctive feature. Hard ferromagnetic irons are also known as hard magnetic materials. Hard irons have their applications as permanent magnets and are used commercially for their unique characteristics. Hard irons have little susceptibility to changes in electric fields, since once they are magnetized or their atoms are aligned they do not reverse or change as easily.

Due to their specific characteristics, hard irons are used in industry in many areas. Steel is slow to magnetization and is retained once magnetized and is classified as hard iron. These magnetized steel bars are used as magnets in loudspeakers and instruments.

What is Soft Iron?

Soft iron is also a ferromagnetic substance, which means that it can act as a magnetic substance in the absence of an electric field. Soft iron is the type of ferromagnetic material. It possesses magnetization, but can be re-magnetized with the use of small changes in electrical force. This change in electrical force is caused by the change in the alignment of the atoms in the substance, which differs from hard iron due to this specific realignment characteristic. Therefore, soft irons are known as soft magnetic materials.

Soft irons have a higher susceptibility to any changes around them caused by the electric field, and their alignment of atoms changes easily with changes in the surrounding field. It is also one of the properties of soft iron that it has a lower retention rate of the alignment of atoms and its alignment of atoms changes every time they are subjected to the electric field. It leads to the acquisition of a particular characteristic that its atoms are temporally aligned and change whenever they are subjected to changes in the electric field in their surroundings. Soft irons also find their use in industry in many areas due to specific characteristics. These are commonly used as electromagnets in motors and generators etc.

Key differences

  1. Hard iron is the kind of ferromagnetic substance that, if magnetized, once cannot be easily demagnetized. On the other hand, soft irons are the type of ferromagnetic iron that can be re-magnetized with the use of a change in electrical force.
  2. Hard irons are known as hard magnetic materials, while soft magnetic substances are known as soft magnetic materials.
  3. Once hard irons are magnetized, they cannot be easily re-magnetized; however, soft iron once magnetized can easily be re-magnetized.
  4. Hard irons are less susceptible to changes in the electric field. On the other hand, soft irons are more susceptible to changes in the electric field in their environment.
  5. Hard irons have more retention of the magnetizing effect once purchased. On the contrary, soft irons retain much less of the acquired charge and are easily demagnetized as soon as the electric field in their surroundings changes.
  6. Hard irons align their atoms almost permanently. However, alignment in soft irons is very temporary.

Final Thought

Hard iron is the kind of ferromagnetic substance that, if magnetized, once cannot be easily demagnetized. In contrast, soft irons are the type of ferromagnetic iron that can be demagnetized with the use of a change in electrical force.

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