A coiled wire around a metal core can be used to make a type of this object that can be turned on and off.
An ironÂ­based type of these objects allows hard drives to store memory and is the strongest type of these objects. A coiled wire around a metal core can be used to make a type of this object that can be turned on and off. (*) FerroÂ­ and electroÂ­ are types of these objects, in which "north" and "south" poles can attract each other. For 10 points, name these metal objects, used to hold papers to refrigerators.
An ironÂ­based type of these objects allows hard drives to store memory and is the strongest type of these objects.
magnets