When you build a circuit in a lab, it may look rather messy, with wires going in various directions and the like. On paper, it's easier to represent circuits as schematic diagrams, such as the one shown in the figure. Wires are represented by lines, and are usually assumed to be ideal wires Ideal wires have zero resistance, and so there is no potential drop across them: their potential is assumed to be the same everywhere, even when current flows through them. (We'll discuss later when this assumption breaks down.) The shape of the schematic diagram doesn't matter, only the order of connections: the fact that a wire connects the battery to the resistor, and another wire connects the resistor back to the battery.
The principle of current conservation TBD says that the current into the resistor is equal to the current out of the resistor. Thus the current through point B is the same as the current through C.
Light bulbs don't emit charge, though; they emit energy, and that's what's being "used up" as the current passes through the light bulb. Charges pick up potential energy as they pass through the battery, and then they release that energy when they fall down the resistor.
It's convenient to think of the electric current as the flow of water in a fountain, with no evaporation. In this analogy, the battery acts as a pump, lifting the water to a higher potential. The water then flows along a short watercourse until it reaches a waterfall (the resistor), where the water drops back down to "ground level" to start over again. As the water falls it might turn a waterwheel which can power a light bulb or other electric device, but otherwise the energy is dissipated into the environment. If there are two waterfalls (resistors), then the total drop (potential)over both waterfalls is equal to the total distance (potential) the water rises in the pump.