Question 12 QMED02 - Electrician-Refrigerating Engineer

The Correct Answer is B **Explanation of Correct Answer (B):** The nominal open-circuit voltage (or resting voltage) of a single, fully charged lead-acid cell is conventionally cited as **2.0 volts**. When fully charged, the chemical reaction (conversion of lead sulfate back into lead dioxide and spongy lead) is complete, and the electrolyte density is at its peak, resulting in this characteristic potential difference between the plates. **Explanation of Incorrect Options:** * **A) 1.5 volts:** This voltage is too low. A lead-acid cell with an open-circuit voltage of 1.5V would be considered heavily discharged (a completely dead cell often rests around 1.8V or below). This value is more typical of a standard alkaline or zinc-carbon cell. * **C) 6 volts:** This is the nominal voltage of a small battery pack made up of **three** lead-acid cells wired in series ($3 \times 2V = 6V$). It is not the voltage of a single cell. * **D) 12 volts:** This is the nominal voltage of a common automotive or deep-cycle battery pack made up of **six** lead-acid cells wired in series ($6 \times 2V = 12V$). It is not the voltage of a single cell.