Select the correct answer from each drop-down menu. William finds a piece of pure iron in his garden. After a few days, the iron begins to rust. What are the two types of substances involved in the rusting process of iron?
Iron is with one kind of atom that combines with oxygen from the air to form rust (iron oxide). Rust contains two types of atoms, which means it is .

stands for electromotive force and it is measured in volts. despite its name, it is not actually the force in the sense of being a "pushing" or "pulling" (not measured in newtons).an equation that relates emf,  ℰ,  to a battery's terminal voltage, v, current, i, and internal resistance, r, is    ℰ = v + irin this case, the emf can be interpreted as a voltage—a difference in electric potential.i would not say that it would be considered an energy. if emf can be defined as the energy/work per a unit charge from a battery or other electric source, then it is not strictly energy.