I know there were previous threads about this but none of these actually pointed out what I am asking for. So if we set the negative terminal in the battery to have 0 potential energy and lets say that Voltage of a battery is 12 volt. So at the positive terminal a one coulomb of charge has 12 joules as the charge moves away from the positive terminal it loses its potential energy and gains it as kinetic energy. Once it encounter load, It takes some of its kinetic energy and change it to another form of energy. What ensures me that this load will take the whole 12 J of energy and the charge will end up gaining or losing nothing at the end of circuit ? That is basically the voltage law. Why not for example the load takes 10 J (just for example) and the rest of the 2 J is in the charge as kinetic energy? That would still conserve the law of conservation of energy.