Which of the following instruments is used to determine the accurate value of the electromotive force of a cell?
Answer Details
The instrument used to determine the accurate value of the electromotive force (emf) of a cell is called a potentiometer. A potentiometer measures the potential difference across a known length of a uniform wire and compares it with the potential difference across the unknown emf source, which is connected in parallel with the wire. By adjusting the length of the wire until the potential difference across the known length is equal to the potential difference across the cell, the emf of the cell can be determined accurately. Therefore, the correct option is a potentiometer.