So for a project what I want to do is experiment with dropping a magnet or a piece of metal down a tube and seeing the effect on its falling speed. My first idea is to wrap copper wire around a piece of PVC pipe. I would then hook it up to a battery to make it into an electromagnet. If the field is to weak then I would try to wrap it around a iron tube to strengthen the effect of the magnetic field instead of the PVC. My question is will it work? I remember once reading somewhere that the field would cancel out in the tube. Thus even if I drop a piece of metal/magnet through it there will be no change. If it is possible to do would it be ok to use a PVC pipe or should it be a iron tube?