What happens to the total voltage when batteries are connected in series?

When batteries are connected in series, the total voltage is the sum of the voltages of each individual battery. This configuration allows each battery to contribute its voltage to the total, effectively increasing the overall voltage available to the circuit. For instance, if you connect two batteries, each rated at 1.5 volts in series, the total voltage provided by the combination would be 3.0 volts. This increase in voltage is a fundamental principle of series connections in electrical circuits, as opposed to parallel connections, where the voltage remains the same as that of one battery while the capacity (amp-hour rating) increases. Thus, in series, the total voltage indeed increases, leading to the correct answer.