With current technologies and solar collectors on the ground, the best we can hope for is that solar cells will generate an average (day and night) power of about 230 watts/m2 . what total area would we need to cover with solar cells to supply all the power needed for the united states? give your answer in both square meters and square kilometers.

Idont understand the question

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.