how hysteresis formed?

Answer 1

Hysteresis is the slight difference between how something reacts going one way compared to how it acts going the other way.

A typical example is a magnet. As it magnetizes, it passes through the origin (the point at which 0 electric field intensity equals 0 magnetic field intensity). This is because the initial charge of magnetism is going into an "empty" container, so to speak.

However, when the magnet is demagnetized (or the field is flipped to the opposite polarity), there will be a small amount of "residual" magnetism from the first charging that will tend to "fight" against the reversal. What this really means is that the reverse polarity charge does not follow the exact same path ... and does not pass through the initial origin at all.

You could look at this as filling and then emptying a glass with water - the first time you fill it, the glass started out completely dry ... which meant you could put X many molecules of water into it. Then you dump it out ... but a few molecules remain adhered to the glass surface (this would be the residual). The next time it's filled, you add as much as the first time (less the residual).

When you empty it again, it leaves a couple of molecules attached. Not necessarily the same ones as the first time, but approximately the same amount. Hence there is now a hysteresis effect occurring when you fill/empty the glass.

Answer 2

Isn't hysteresis just a measurement of slop? Let's say you tell a valve to control pressure to 40 Torr so you move the valve to that point, then you move the valve 300 steps and then move it back 300 steps and get 41 Torr and it takes another 15 steps to get to 40 Torr, the hysteresis would be 15. I don't know how it is formed though, that's just how it is measured. At least in my experience.

Answer 3

There are lots of different 'types' of hysteresis -- wikipedia does a very good job of describing them. Check the link.

Answer 4

What is hysteresis?