sentences: coiled wires are a kind of wire & an electromagnet is made of coiled wires, iron core, and source of electricity ->  an electromagnet is made of wires, iron core, and a source of electricity  an electromagnet is made of wires, iron core, and a source of electricity & iron rod can be used as an iron core & a battery is a source of electrical energy / electricity & an insulated wire is a kind of wire -> insulated wire, iron rod, and battery can build an electromagnet