Which of the following values represents an index of refraction of an actual material?
a. 0
b. 1 / 4
c. 5 / 4
d. 1 / 2

C. 5/4, in order for light to be refracted the refraction index has to be greter than 1

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.