Final answer:
In a series combination, the sum of the potential differences for the two light bulbs is less than the potential difference across the battery.
Step-by-step explanation:
In a series combination, the potential difference across each light bulb is the same. To find the sum of the potential differences for the two light bulbs, you simply add them together. Let's say the potential difference across each light bulb is 4 volts. Therefore, the sum of the potential differences for the two light bulbs would be 4 volts + 4 volts = 8 volts.
In comparison, the potential difference across the battery is the total potential difference across the entire circuit. So if the battery has a potential difference of 12 volts, then the potential difference across the battery is 12 volts. Therefore, in this case, the sum of the potential differences for the two light bulbs (8 volts) is less than the potential difference across the battery (12 volts).
For instance, if a circuit has a battery of 12.0 volts, and you have two light bulbs in series, the sum of the potential differences across the light bulbs must equal the potential difference of the battery. Therefore, if you were to measure the voltage across each light bulb and add those voltages together, it would be the same as the voltage of the battery itself. This is because, in a series circuit, current is constant but the voltage divides according to the resistances of the individual components.