Which statement best describes the effect of opposing polarity sources in series on the net voltage?

• A. The algebraic sum considering polarity
• B. The largest source
• C. Always zero
• D. The average

Answer: (A)

When sources with opposite polarity are placed in series, the net voltage is found by adding their voltages with proper signs. The algebraic sum takes into account the direction each source pushes voltage, so you effectively subtract the smaller opposing voltage from the larger and keep the sign of the larger one. For example, if a 12 V source opposes a 5 V source, the net voltage is 7 V in the direction of the 12 V source. If the magnitudes are equal, the net voltage is zero; otherwise, it’s the difference with the appropriate orientation. This approach is why you don’t just take the largest, nor the average.