Hysteresis: Magnetism Lags Behind Current

In summary, the conversation discussed the concept of hysteresis and how it affects the relationship between magnetization and magnetizing current in a system. Hysteresis causes a lag between changes in current and changes in magnetic flux, making it difficult to predict the instantaneous state of the system without understanding its history. The capitalized portion of the conversation explained that the magnitude of magnetic flux is influenced by the magnitude of the magnetizing current, but these changes in flux take time to occur and always lag behind the changes in current. The conversation also included a Wikipedia page on hysteresis and a correction of a typo in the original text. Overall, the conversation helped clarify misconceptions about hysteresis.
  • #1
uzair_ha91
92
0
Can anyone explain the following lines? [Only the bit where the letters are capitalized]
"The flux density versus the magnetization of the specimen for the various values of the magnetizing current of the solenoid is plotted by a CRO...from the figure, we can conclude that value for flux density for any value of current is always greater when current is decreasing than when it's increasing, I.E. MAGNETISM LAGS BEHIND THE MAGNETIZING CURRENT. This phenomenon is known as hysteresis."
 
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  • #2
Hysteresis exists in systems in which effects lag causative mechanisms, so there is not a reliable way to predict the instantaneous state of the system without having an understanding of the history of the system. When the magnetizing current is increasing, the magnetic flux is also increasing, but lagging the increase in current. When the magnetizing current is decreasing, the magnetic flux also reduces, but is stronger than one might expect (calculating from instantaneous values) because of the time it takes for the flux to moderate as the magnetizing current is removed. The capitalized portion of your post explains that the magnitude of the magnetic flux in the system rises and falls with the magnitude of the magnetizing current BUT these changes in flux take time to occur and always lag behind the changes in current.
 
  • #3
Here in thumbnail is a page extracted from Wikipedia on hysteresis. The horizontal axis is the current in amps (amp turns per meter) and the vertical axis is field strength (Tesla). When a hysteresis curve data is neasured, the measurement points go around the loop in a counterclockwise direction. For a given number of amps, the field is higher (lagging) when the direction of the current is decreasing.
 

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  • #4
Thanks for the efforts, the answers you guys posted have cleared my misconceptions about hysteresis :-)
 
  • #5
And I think there's a typo in my post [the 1st line of the text I quoted] : "The flux density versus the magnetization CURRENT of the ..."
 

What is hysteresis in magnetism?

Hysteresis in magnetism refers to the phenomenon where the magnetic properties of a material lag behind changes in the applied magnetic field. This means that even after the magnetic field is removed, the material retains a residual magnetization.

What causes hysteresis in magnetism?

Hysteresis in magnetism is caused by the alignment of magnetic domains within a material. When a magnetic field is applied, these domains align with the field, but when the field is removed, the domains do not immediately return to their original state, resulting in hysteresis.

How is hysteresis measured?

Hysteresis is measured by plotting the relationship between the applied magnetic field and the resulting magnetization of a material. This is known as a hysteresis loop, and the area inside the loop represents the energy lost due to hysteresis.

What are some practical applications of hysteresis in magnetism?

Hysteresis is used in various applications such as magnetic storage devices, motors, and transformers. It allows these devices to retain a magnetic memory and maintain a stable output even in the presence of fluctuating magnetic fields.

Can hysteresis be eliminated?

Hysteresis cannot be completely eliminated, but it can be reduced by using materials with lower coercivity (the amount of magnetic field required to demagnetize a material). Additionally, using alternating current instead of direct current can also help reduce hysteresis effects.

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