A potential difference meter is an instrument constructed using the principle of compensation. A high-precision measuring instrument made based on the principle of mutual compensation between the measured voltage and the known voltage. There are two types: AC and DC. Used to measure voltage, current, and resistance, AC potentiometers can also measure magnetism.
There are many types of potentiometers, commonly including plate and box potentiometers [1]. The plate type potential difference meter has the advantages of simple structure, intuitiveness, and easy analysis and discussion. However, its resistance wire cannot be completely uniform, and its length is not very accurate. There is a certain measurement error, and it is large in size and inconvenient to use. The box type potential difference meter overcomes the shortcomings of the plate type potential difference meter, with higher accuracy and more practicality.