Hysteresis Curve
- Hysteresis Mens Lagging The Lagging Of Intensity Of
Magnetization (B) Behind The Intensity Of Magnetic Fild (H)
- Hysteresis Occurs In A System That Involves A Magnetic Field.
Hysteresis Is A Common Property Of Ferromagnetic Substances.
- All Ferromagnetic Materials Exhibit The Phenomena Of
Hysteresis.
- Ferromagnetic Substance Is Placed Inside A Current-Carrying
Coil. Due To The Magnetic Field That Is Present, The Substance
Gets Magnetized.If We Reverse The Direction Of The Current,
Then The Substance Gets Demagnetized, And This Process Is
Known As Hysteresis.
Hysteresis Loop :
- A Graph Is Drawn Between The Intensity Of Magnetization (B)
And Intensity Of Magnetic Fild (H)
- When The Intensity Of Magnetic Fild H Is Increased From
Zero,The Intensity Of Magnetism Is Also Increased
- Futher Increasing The Value Is Also Increased And Finally
Reaches The Saturation Piont A In Figure.Ie. B Is Constant.
- Then Decreasing The Value Of H,The B Valuse Is Also Decresed,
But At The Point H=O,But B=0.Now The Material Retains Some
Amount Of Magnetism Is Known As Retentiity Or Resudial
Magnetism
- Futher Decreasing The Value Of H In Nagative Side,The B Value
Is Also Decreased At The Point C The Material Is Fully
Demagnetized.The Force Is Required For Remove The Resudial
Magnetism Is Called Coercive Force
- The Cycle Is Continue In Opposite Directio As Shown Fig D Is
Saturation Point ,E Is Retentivity And F Is The Coercive Force In
Negative Direction.The Cycle Is Completed, Itmake The
Hysteresis Loop
- Understanding Magnetic Behavior
- Magnetic Memory
- Magnetic Characterization
- Magnetic Energy Storage
- Magnetic Material Selection
- Magnetostrictive Applications
- Magnetic Device Design
Retentivity And Coercivity :
Retentivity:
- The Amount Of Magnetization Present When The External
Magnetizing Field Is Removed Is Known As Retentivity.
- It Is A Material’s Ability To Retain A Certain Amount Of
Magnetic Property While An Externa l Magnetizing Field Is
Removed.
- The Value Of B At Point B In The Hysteresis Loop.
Coercivity:
- The Amount Of Reverse (-Ve H) External Magnetizing Field
Required To Completely Demagnetize The Substance Is Known
As The Coercivity Of The Substance.
- The Value Of H At Point C In The Hysteresis Loop.
Hysteresis Applications :
- Magnetic Switches: Hysteresis Is Employed In Magnetic
Switches Or Relays To Ensure Stable And Reliable Operation.
- Thermostats: Hysteresis Is Used In Thermostats To Control
Heating And Cooling Systems.
- Control Systems: Hysteresis Is Employed In Control Systems To
Prevent Chattering Or Rapid Oscillations Around The Desired
Setpoint.
- Memristors: Hysteresis Is Utilized In Memristor Devices, Which
Are A Type Of Electronic Component That Can Remember Its
Resistance State.
- Loudspeaker And Microphone Diaphragms: Hysteresis Is
Considered In The Design Of Loudspeaker And Microphone
Diaphragms To Ensure Smooth And Accurate Sound
Reproduction.
- Ferroelectric Materials: Ferroelectric Materials Exhibit
Hysteresis In Their Polarization-Electric Field Relationship.This
Property Is Utilized In Various Applications,Including Non-
Volatile Memory Devices (E.G., Ferroelectric RAM), Sensors,
Actuators, And Capacitors.
Energy Loss Due To Hysteresis :
- During The Cycle Of Magnetization And Demagnetization Of
Magnetic Substances, Energy Is Spent,And This Spent Energy
Appears In The Form Of Heat.This Heat Loss Is Known As
Hysteresis Loss.
- The Loss Of Energy Per Unit Volume Of The Substance Is Equal
To The Area Of The Hysteresis Curve.
- In Transformers, Due To The Continuous Process Of
Magnetization And Demagnetization, Energy Is Lost In The
Form Of Heat Continuously,Due To This, The Energy Loss
Efficiency Of The Transformer Gets Reduced.
- To Stop This Energy Loss, A Soft Iron Core Is Used In
Transformers Because The Energy Loss Or Hysteresis Loss In
The Case Of Soft Iron Is Much Smaller Than In Other Materials.
Soft magnet :
- Easily magnetized and demagnetized
- It can be produced by heating and slow cooling
- Hysteresis loop area is small
- Retentivity is small
- Coercivity is small
- Energy product value is small
- Eddy current loss is small
- It’s temporary magnet
- Ex. Silicon allyo ferrous nickel etc
- Use:electromagnet,computer data storage etc
Hard magnet :
-Can not Easily magnetized and demagnetized
-It can be produced by heating and sudden cooling
-Hysteresis loop area is high
-Retentivity is high
-Coercivity is high
-Energy product value is high
-Eddy current loss is high
-It’s permanent magnet
-Ex. Alinico,tungsten steel etc
-Use: Dc magnet
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