To measure the potential difference across a cell, where are the voltmeter leads placed?

To measure the potential difference across a cell, where are the voltmeter leads placed?

• A. Across the entire circuit
• B. To each side of the cell
• C. In series with the circuit
• D. Across the power supply only

Answer: (B)

A voltmeter measures the potential difference between two points, so it must be connected in parallel with the element you want to measure. To measure the voltage across a cell, place the leads on the two terminals of the cell. This configuration lets the meter read the cell’s voltage without drawing significant current, thanks to the voltmeter’s high resistance, so the circuit isn’t noticeably affected. Connecting the voltmeter elsewhere—across the entire circuit, in series with the circuit, or only across the power supply—would not read the cell’s voltage specifically.

A voltmeter measures the potential difference between two points, so it must be connected in parallel with the element you want to measure. To measure the voltage across a cell, place the leads on the two terminals of the cell. This configuration lets the meter read the cell’s voltage without drawing significant current, thanks to the voltmeter’s high resistance, so the circuit isn’t noticeably affected. Connecting the voltmeter elsewhere—across the entire circuit, in series with the circuit, or only across the power supply—would not read the cell’s voltage specifically.