Iron surface

[zesla]

Hello guys,

I want to know if I apply a DC voltage to the wire wounding then what will happen to the iron surface and why? What if the voltage happens to be AC??
I think that the iron surface will move but how and why, I am not sure...

Thanks for any help

 

[JimB]

I want to know if I apply a DC voltage to the wire wounding then what will happen to the iron surface and why?

I assume that you mean winding, not wounding,
and that the iron "surface" is the piece at the top, which is partially covering the gap in the core of the winding,
and that the core of the winding is made from magnetic material.

Then, if the current is large enough, and there are sufficient turns of wire, the iron piece will move to cover the gap in the core.

What if the voltage happens to be AC??

It will move to cover the gap and make a buzzing noise.

JimB

 

[crutschow]

The iron pole piece will move to fill the gap since the magnetic flux lines in a magnetic circuit always tries to minimize the circuit magnetic reluctance and iron has less reluctance than air. It's how a solenoid or reluctance motor works.

 

[hannobisschoff@gmail.com]

What are you going to use this for?

 

[zesla]

I assume that you mean winding, not wounding,
and that the iron "surface" is the piece at the top, which is partially covering the gap in the core of the winding,
and that the core of the winding is made from magnetic material.

Then, if the current is large enough, and there are sufficient turns of wire, the iron piece will move to cover the gap in the core.



It will move to cover the gap and make a buzzing noise.

JimB

Thanks sir,

but Why the polarity of the power supply is not important for the direction of the iron piece?

 

[zesla]

The iron pole piece will move to fill the gap since the magnetic flux lines in a magnetic circuit always tries to minimize the circuit magnetic reluctance and iron has less reluctance than air. It's how a solenoid or reluctance motor works.

seems reasonable.
Thanks a bunch sir.
But what if the power source happens to be AC?

 

[crutschow]

........But what if the power source happens to be AC?

The reluctance is independent of the magnetic polarity and thus independent of the direction of current through the coil.

 

[zesla]

The reluctance is independent of the magnetic polarity and thus independent of the direction of current through the coil.

oh! But I was trying to find a relationship between the direction of the piece and the magnetics filed of the lower surface, So I was completely on the wrong side?

So please tell me if there is ANY deference if I apply DC or AC power to the construction?

Thanks

 

[crutschow]

oh! But I was trying to find a relationship between the direction of the piece and the magnetics filed of the lower surface, So I was completely on the wrong side?

So please tell me if there is ANY deference if I apply DC or AC power to the construction?

A current through the coil will always attract the pole piece to fill the gap, independent of polarity.

One difference between DC and AC is that AC may cause buzzing when the pole closes the gap. And there are other secondary AC effects like the coil inductance reducing the current as compared to DC for a given voltage, and heat losses from eddy currents in the magnetic material.

 

[MrAl]

Hello guys,

I want to know if I apply a DC voltage to the wire wounding then what will happen to the iron surface and why? What if the voltage happens to be AC??
I think that the iron surface will move but how and why, I am not sure...

Thanks for any help

Hi there,

If you think about it as two magnets, the upper magnet will move to close the gap because the open faces will attract each other, regardless of the polarity of the magnetization (its in the same direction for both pieces). Reversing the current just reverses the polarity of both faces, but they will still attract because they will be opposite poles.
There's a little catch here though. As the upper magnet (the one that moves) becomes magnetized in one direction, its coercive force could require that some new level of reverse magnetization that exceeds a certain threshold be attained before it will itself reverse magnetization. This means that for a lower level AC the upper magnet might just move back and forth until a certain magnitude is reached sufficient to reverse its magnetization.
Would be an interesting experiment if you feel like setting it up.

The classical problem set up like this one is to calculate the motion of the upper iron part as the lower part is magnetized in a certain direction.

 

[zesla]

Ok thanks a bunch guys, It makes sense now,

The last question is if there is any formula/relationship for the said pic saying why it does move so that fill the gap?

Thank