When multiple sources are in series with opposing polarities, the net electromotive force can be less than any single source's magnitude.

• A. Only if there is a short circuit
• B. Only if all sources are identical
• C. True
• D. False

Answer: (C)

When voltage sources are in series, their voltages add with signs that reflect their orientation. If two or more sources point in opposite directions, their EMFs subtract from each other. The net electromotive force is the algebraic sum of the individual EMFs, so opposing voltages can cancel part of the others. This means the overall EMF can be smaller than any one source’s magnitude, even to the point of zero if the opposing values match exactly. There’s no requirement for a short circuit, and the sources don’t have to be identical for cancellation to occur. For example, a 12 V source in opposition to a 9 V source leaves a net 3 V. That shows why the statement is true.