Empty lamp

Solution in terms of the strength of current

A battery primarily consists of two separated cells. One cell is filled with a substance which emits electrons very easily, there we have a surplus of electrons. The other cell is filled with a substance which absorbs electrons very easily, there we have a lack of electrons. If these cells are connected by a circuit, they can react with each other. Thereby, electrons pass through the conductor from the first to the second substance, electric current flows.. (The property of substances to have a surplus or a lack of electrons can also be seen in terms of frictional electricity.)

The current continues flowing until the conductive connection between the cells will be disconnected or until the differences of electrons between them is compensated. So if the electric circuit is closed, the electrons transit the light bulb of the lamp so that it shines. But if the amount of electrons in the two cells of the battery is balanced out, the current flow will come to a standstill.