what is hysteresis loop?

Answer 1

*Hysteresis loop :
A graph of magnetizing force vs. remanent magnetization.
*If the displacement of a system with hysteresis is plotted on a graph against the applied force, the resulting curve is in the form of a loop. In contrast, the curve for a system without hysteresis is a single, not necessarily straight, line. Although the hysteresis loop depends on the material's physical properties, there is no complete theoretical description that explains the phenomenon. The family of hysteresis loops, from the results of different applied varying voltages or forces, form a closed space in three dimensions, called the hysteroid.

Hysteresis was initially seen as problematic, but is now thought to be of great importance in technology. For instance, the properties of hysteresis are applied when constructing permanent memory for computers: hysteresis allows most superconductors to operate at the high currents needed to create strong magnetic fields. Hysteresis is also important in living systems. Many critical processes occurring in living (or dying) cells use hysteresis to help stabilize them against the various effects of random chemical fluctuations.

Some early work on describing hysteresis in mechanical systems was performed by James Clerk Maxwell. Subsequently, hysteresis models have received significant attention in the works of Preisach, Neel and Everett in connection with magnetism and absorption. A simple parametric description of various hysteresis loops may be found in ref. [1] (with the model, substitution of rectangle, triangle or trapezoidal pulses instead of the harmonic functions also allows to built piecewise-linear hysteresis loops frequently used in discrete automatics). More formal mathematical theory of systems with hysteresis was developed in 1970s, by a group of Russian mathematicians, which was led by Mark Krasnosel'skii, one of the founders of nonlinear analysis. He suggested an investigation of hysteresis phenomena using the theory of nonlinear operators.

*If this relationship is plotted for all strengths of applied magnetic field the result is a sort of S- shaped loop. The 'thickness' of the middle bit of the S describes the amount of hysteresis, related to the coercivity of the material.

Its practical effects might be, for example, to cause a relay to be slow to release due to the remaining magnetic field continuing to attract the armature when the applied electric current to the operating coil is removed.


Hysteresis loop: magnetization (M) as function of magnetic field strength (H)This curve for a particular material influences the design of a magnetic circuit.

This is also a very important effect in magnetic tape and other magnetic storage media like hard disks.

Answer 2

Hysteresis Loop Definition

Answer 3

hysteresis loop is a graph showing hysteresis . hysteresis occur when we receive different output (increase or decrease in the results)of an experiment done in the same surrounding.
There are many factors that causes hysteresis. some of them are Friction, Air Resistance, Vibrations. (It actually depends on the effect external elements can do on an experiment .)
The definition of the hysteresis differ for electrical and Mechanical. (general definition : it is error).

Wikipedia is not a good source to learn technological term......

Answer 4

It is when someone on yahoo asks a question over and over and over again!