10. a) On the diagram of an old-fashioned electric doorbell below, label any relevant N or S magnetic poles that arise when point A is closed--and note the effect this will have on the magnetic domains of the steel bar. b) Given that the steel bar and its attached hammer and wire is free to move, explain why pressing down on Point A causes the gong to be struck repeatedly by the hammer at the end of the steel metal bar. wire steel bar contact screw ammer