A curved steel ball forms image of an object at 21 cm behind from face one and at 7 cm behind from opposite face. Find the radius of curvature of the ball.

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.

When you go to ask a qustion there will be a picture of a paper clip looking thing and then it will pop up your files and you click on the imajes and then you up load it