In an electromagnet with an iron or similar core, how far down that core, beyond the coil, will the rod be magnetic when the coil is energized?
I'm wondering if I can create an actuator for an object inside a sealed container. The rod would enter the container, with an electromagnet outside the container. A magnetic sleeve on the rod, inside the container, could then be moved toward or away from the end of the container by energizing the electromagnet, if the magnetic force extended a sufficient distance down the rod.
This obviously depends on how far down the rod (core) the magnetic effect extends.