A room measuring 21 m by 18 m and 13 m high has to be lighted by four lighting fixtures suspended 3 m from ceiling. The ceiling points are symmetrically placed on the two diagonals so that each point is 7 m from the center of the ceiling. An illumination of 12 lux apart from any effect due to the walls and ceiling is required on the center of a table 3 m high placed at the center of the room. What luminous intensity must each unit give in direction necessary to produce this result?

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.