Final answer:
The voltage across the battery in a series circuit is the sum of the voltages across each resistor; in a parallel circuit, it is equal to the voltage across each resistor.
Step-by-step explanation:
To determine the voltage across the battery in a circuit with resistors, we employ Ohm's Law and the principles of series and parallel circuits. In a series circuit, the voltage across the battery is the sum of the voltages across each resistor, as expressed by the formula Vbattery = V1 + V2 + .... Conversely, in a parallel circuit, the voltage across each resistor is equal to the voltage across the battery. Therefore, if you have a parallel circuit with resistors all having a voltage of 2 V, then the voltage across the battery is also 2 V. This is because the voltage in a parallel circuit remains constant across all components.
Thus, when dealing with series circuits, you add up the voltages across each resistor to find the voltage across the battery, whereas, in parallel circuits, the voltage across the battery is equal to the voltage across each individual resistor.