When power supplies are connected in parallel, what remains constant?

• A. Current
• B. Resistance
• C. Voltage
• D. Power

Answer: (C)

When power supplies are connected in parallel, the voltage across each power supply remains constant. This is a fundamental principle of parallel circuits, where each component experiences the same potential difference.

In a parallel configuration, the positive terminals of the power supplies are connected together, as well as the negative terminals, ensuring that all supplies share the same voltage level. This uniformity in voltage is essential for the proper functioning of devices powered by these supplies, as it allows them to operate at a consistent potential.

The current, on the other hand, can vary depending on the individual power supply characteristics and the load connected to them. The total current drawn from the parallel power supplies is the sum of the currents from each individual source, which is why it does not remain constant.

Resistance in a parallel circuit doesn’t remain constant either, as the total resistance can decrease when additional paths for current flow are added. The total power supplied by the sources is also not constant as it depends on the total current draw and can increase with more power supplies in parallel.

Thus, the constancy of voltage in a parallel configuration is critical to ensuring that all components operate effectively at the same voltage level, making it the correct answer to the question at hand.