Electromagnetism with an iron core

[sgstudent]

Homework Statement

When we have an iron core in a solenoid, the iron core will become magnetised. But if I were to put a piece of iron in front of the iron and solenoid the piece of iron will come out like in a door chime. But as it comes out, will the magnetic field be stretched and elongated? The mechanism is something like this animation http://home.howstuffworks.com/home-improvement/repair/doorbell3.htm

So if we draw the magnetic field of the solenoid and iron, will the field at the end facing the solenoid be stretched such that when the field leaves the iron bar it stretches out all the way to the end of the solenoid? So in order words it's like have a bar magnet and just lengthening it?

Homework Equations

None

The Attempt at a Solution

I think so, just that at one end (not the iron part) is weaker as the iron bar does not concentrate the magnetic field lines? So only the part closest to the iron bar on both ends are equally strong as each other? I will draw some pictures to make this clearer. Thanks!

Here is the link to the picture: www.imgur.com/wGTvp oops I meant the whole field "belongs" to the solenoid rather than iron.

 

[member 553083]

Sorry. Yes, I believe the magnetic field at the end facing the solenoid will be stretched such that when the field leaves the iron bar it stretches out all the way to the end of the solenoid. The magnetic field lines will be focused around the iron bar, and then spread out as they travel away from it. The strength of the field lines at the end of the solenoid will be weaker than at the beginning, but the overall shape of the magnetic field will be elongated.