Which polarity configuration is described as additive?

• A. Additive
• B. Subtractive
• C. Neutral
• D. Bipolar

Answer: (A)

When you connect transformer windings in series, polarity determines whether the voltages reinforce or oppose each other. Additive polarity means the EMFs add in the same direction, so the total voltage is the sum of the individual voltages. This happens when the ends marked with the same polarity (the dots) are connected together and the remaining ends form the output; the voltages are in phase, giving a higher combined voltage.

For example, two 50 V windings with additive polarity yield 100 V across the series connection when their matching polarity ends are tied together. If opposite polarities are connected, the voltages subtract, producing a lower voltage equal to their difference.

So the configuration described as additive is the one where the voltages reinforce each other. Subtractive describes the opposite case; neutral and bipolar aren’t the terms used to describe this polarity relationship in transformer windings.