With same orientation, the potential difference across the chain is

• A. The smallest single voltage
• B. Zero
• C. The sum of their voltages
• D. The average of the voltages

Answer: (C)

When voltage sources are connected in series with the same polarity, their voltages add to produce the total potential difference across the ends. Each source raises the potential as you move from one end to the other, so the rises stack: the total is V1 + V2 + V3 + … . This follows from the loop rule: the sum of emfs around the chain equals the overall emf across the ends. For example, two 1.5 V cells in series give about 3.0 V. If orientations oppose each other, you’d subtract instead, and the total could be smaller or zero if the values match.