Since you're using Illustrator then use the tools built into it for doing exactly what you're doing. But if you don't have / want to use the Adobe software there are several free alternatives:

Potrace is Free (as in FOSS) vectorisation software, these days it comes as a plugin for the free vector graphics package Inkscape

The brilliant commercial / open source vector graphics package Xara is available free for Linux, it has an excellent built-in tracing tool (and it kicks illustrator's 4rse for speed and ease of use)

Other free vectorisation software includes AutoTrace and Deliniate.

Also there's a free web app called vector magic here, they sell a desktop version as well.

-stib

Photoshop/Illustrator: generate vector graphic from bitmap
What will be the maximum magnetic strength to which a piece of ferromagnetic substance can be magnetised?

What will the maximum strength possible for a piece of iron?

How would the shape of the ferromagnetic substance affect this strength?

What would be the current needed in the solenoid if this strength is to be achieved?
