Magnetization and Demagnetization

The method of developing magnetic properties inside a magnetic substance is known as magnetization. With the aid of an electric current or a powerful magnet, any magnetic material may be magnetised.

  • In simple terms, if any magnetic substance is placed in an external magnetising field, the material will become magnetised, and if the external magnetising field is reversed, the material will become demagnetized.
  • When ferromagnetic materials are put inside a current-carrying coil, the magnetising field H produced by the current pushes some or all of the material’s atomic magnetic dipoles to align with the external magnetising field, magnetising the material.

Hysteresis Loop

Hysteresis Loop– In a system with a magnetic field, hysteresis occurs. Ferromagnetic materials have a common characteristic called hysteresis. The hysteresis effect is a phenomenon that occurs when the magnetization of ferromagnetic materials lags behind the magnetic field.  The word hysteresis means “lagging.” Magnetic flux density (B) lags after magnetic field strength, resulting in hysteresis (H).

Hysteresis is a property of all ferromagnetic materials. Let’s look at an example where a ferromagnetic material is placed within a current-carrying coil to better grasp the notion. The material becomes magnetized as a result of the magnetic field present. Hysteresis is known as the process of demagnetizing a material by reversing the direction of the current.

Table of Content

  • Hysteresis Loop
  • Difference between the soft magnets and hard magnets
  • Magnetization and Demagnetization
  • Sample Problems

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Hysteresis Loop

The magnetic flux density and the magnetising field strength are represented by the hysteresis loop. The loop is created by monitoring the magnetic flux emitted by the ferromagnetic material while the external magnetising field is changed....

Advantages of Hysteresis Loop

The loss of hysteresis is shown by a decreased area of the hysteresis loop. The relevance of retentivity and coercivity is provided by the hysteresis loop to a material. As a result, the heart of machines makes it easier to choose the correct material for making a permanent magnet. The B-H graph may be used to determine residual magnetism, making a material selection for electromagnets straightforward....

Retentivity and Coercivity

After an external magnetising field is used to magnetise a ferromagnetic material, the material will not relax back to its zero magnetization state when the external magnetising field is removed....

Energy Loss due to Hysteresis

The greatest example of analysing energy loss due to hysteresis is a transformer because we know that energy is required throughout the magnetization and demagnetization processes. Energy is expanded during the magnetization and demagnetization of magnetic objects, and this expanded energy manifests as heat. Hysteresis loss is the term for this type of heat loss. Due to the continuous process of magnetization and demagnetization in transformers, energy is continuously lost in the form of heat, reducing the transformer’s efficiency. Soft iron cores are used in transformers to prevent energy loss because the energy loss or hysteresis loss in soft iron is significantly lower than in other materials....

Difference between the soft magnets and hard magnets

In comparison to hard magnets, soft magnets magnetise and demagnetizes readily. The retentivity of soft magnets is higher than that of hard magnets. Hard magnets have a coercivity that is higher than that of soft magnets. Soft magnets lose less energy than hard magnets due to their tiny surface area. In the case of soft magnets, the loop area is less than that of hard magnets. Soft magnets have higher magnetic permeability than hard magnets. In soft magnets, I and χ are both high, but in hard magnets, they are both low. Soft magnets are temporary magnets while hard magnets are permanent magnets. Ferrous-nickel alloy, Ferrites, etc. are examples of soft magnets while carbon steel, steel, tungsten, chromium steel, etc. are examples of hard magnets....

Magnetization and Demagnetization

The method of developing magnetic properties inside a magnetic substance is known as magnetization. With the aid of an electric current or a powerful magnet, any magnetic material may be magnetised....

Sample Problems

Problem 1: Which materials have the narrowest hysteresis loop?...

Hysteresis Loop – FAQs

What is a hysteresis loop?...