What is Hysteresis Loop?

A hysteresis loop is a graphical representation of the relationship between the magnetic field strength (H) and the magnetization (M) of a material. It is obtained by plotting the magnetization of a material as a function of the applied magnetic field strength.

Key Points

• Hysteresis loops are used to characterize the magnetic properties of materials.
• The shape of the hysteresis loop depends on the material’s magnetic properties.
• Hysteresis loops can be used to determine a material’s coercivity, remanence, and saturation magnetization.

Types of Hysteresis Loops

There are three main types of hysteresis loops:

• Paramagnetic materials have a linear hysteresis loop. This means that the magnetization of the material is proportional to the applied magnetic field strength.
• Diamagnetic materials have a negative slope hysteresis loop. This means that the magnetization of the material is opposite to the applied magnetic field strength.
• Ferromagnetic materials have a non-linear hysteresis loop. This means that the magnetization of the material does not change proportionally to the applied magnetic field strength.

Applications of Hysteresis Loops

Hysteresis loops are used in a variety of applications, including:

• Magnetic recording: Hysteresis loops are used to design magnetic recording media, such as hard disk drives and magnetic tape.
• Magnetic sensors: Hysteresis loops are used to design magnetic sensors, such as Hall effect sensors and magnetoresistive sensors.
• Magnetic materials: Hysteresis loops are used to characterize the magnetic properties of materials, such as their coercivity, remanence, and saturation magnetization.

Hysteresis loops are a valuable tool for understanding the magnetic properties of materials. They can be used to design magnetic recording media, magnetic sensors, and magnetic materials.

What is Hysteresis Loss?

Hysteresis loss is the energy lost when a material is subjected to a changing magnetic field. It is caused by the fact that the magnetization of a material does not change instantaneously when the magnetic field changes. This lag in magnetization results in a loss of energy, which is dissipated as heat.

How Does Hysteresis Loss Occur?

When a material is subjected to a magnetic field, its magnetic domains align themselves with the field. This alignment creates a net magnetic moment in the material. When the magnetic field is removed, the magnetic domains do not immediately return to their original orientations. Instead, they relax slowly, over time. This relaxation process is called hysteresis.

The energy lost during hysteresis is due to the work done by the magnetic field in aligning the magnetic domains. This work is dissipated as heat. The amount of energy lost depends on the material’s hysteresis loop.

Hysteresis Loop

A hysteresis loop is a graph of the magnetization of a material as a function of the magnetic field strength. The shape of the hysteresis loop depends on the material’s properties.

Materials with High Hysteresis Loss

Materials with high hysteresis loss are used in applications where it is important to dissipate energy, such as brakes and transformers.

Some materials with high hysteresis loss include:

• Iron
• Steel
• Nickel
• Cobalt

Materials with Low Hysteresis Loss

Materials with low hysteresis loss are used in applications where it is important to minimize energy loss, such as motors and generators.

Some materials with low hysteresis loss include:

• Silicon steel
• Permalloy
• Metglas

Hysteresis FAQs

What is hysteresis?

Hysteresis is the dependence of the output of a system on its previous inputs. In other words, the output of a system with hysteresis depends not only on its current input, but also on its past inputs.

What causes hysteresis?

Hysteresis can be caused by a number of factors, including:

• Friction: Friction can cause hysteresis in mechanical systems. For example, when a car is moving, the friction between the tires and the road causes the car to slow down. When the car stops, the friction between the tires and the road causes the car to stop.
• Magnetic hysteresis: Magnetic hysteresis occurs when a magnetic material is subjected to a changing magnetic field. The magnetic material will retain some of its magnetism even after the magnetic field is removed.
• Electrical hysteresis: Electrical hysteresis occurs when an electrical circuit is subjected to a changing voltage or current. The electrical circuit will retain some of its charge even after the voltage or current is removed.

What are the effects of hysteresis?

Hysteresis can have a number of effects on a system, including:

• Delay: Hysteresis can cause a system to respond to inputs with a delay. For example, a car with hysteresis will take longer to stop than a car without hysteresis.
• Oscillation: Hysteresis can cause a system to oscillate. For example, a magnetic material with hysteresis will oscillate when it is subjected to a changing magnetic field.
• Instability: Hysteresis can cause a system to become unstable. For example, an electrical circuit with hysteresis can become unstable when it is subjected to a changing voltage or current.

How can hysteresis be reduced?

Hysteresis can be reduced by a number of methods, including:

• Reducing friction: Reducing friction can reduce hysteresis in mechanical systems. For example, using lubricants can reduce friction between moving parts.
• Using materials with low hysteresis: Using materials with low hysteresis can reduce hysteresis in magnetic and electrical systems. For example, using soft iron instead of hard iron can reduce magnetic hysteresis.
• Using feedback control: Feedback control can be used to reduce hysteresis in systems. For example, a feedback control system can be used to control the voltage or current in an electrical circuit to reduce electrical hysteresis.

Conclusion

Hysteresis is a common phenomenon that can have a number of effects on a system. By understanding the causes and effects of hysteresis, engineers can design systems to minimize the negative effects of hysteresis.